Here is some information i gleaned from the WorldofWarcraft.com Forums, as stated by Blizzard Community MVP Frejya

1. General Information
a. Miscellaneous
– Level Cap raised to 85
– New Race/Class combinations: Blood Elf (Warrior), Dwarf (Shaman, Mage), Gnome (Priest), Humans (Hunter), Night Elf (Mage), Orc (Mage), Tauren (Paladin, Priest), Troll (Druid), Undead (Hunter)
– Two new races – Goblins and Worgen (see below)
– Path of the Titans and Mastery (see below)
– No new talents (we will be able to spend our 5 new talent points in the existing trees, they just will not be extended)
– No new classes
– Deathwing is the main threat this time around (http://www.wowwiki.com/Deathwing)

b. Mounts
– Flying Mounts: now usable in the newly revamped Old World; Unknown at this time: if in all areas, if at all levels, if there will be an ‘unlocking’ requirement similar to Wrath
– Underwater Mounts are coming!
– Possibility of multi-passenger flying mounts!

2. New Races
a. Worgen
– Worgen, the new Alliance race, will have their own district in Stormwind. They have a worgen form and a human (cosmetic) form; when in combat the worgen will always shift to the worgen form.
– Worgen will have access to all classes except paladin and shaman.
– Racials: Darkflight: allows the worgen to temporarily increase their movement speed by 70%, and can be used every three minutes; Aberration: reduced duration from the effects of curses and disease; Flayer: bonus to skinning, as well as the ability to skin faster and not use a skinning knife; Viciousness: 1% bonus to damage
– Mount: http://www.wowwiki.com/File:Worgen_mount.jpg (pig/bear looking thing)
– Starting Zone: Gilneas

b. Goblins
– Goblins, the new Horde race, will have a city (not confirmed to be a capital)in the revamped zone of Azshara.
– Goblins will have access to all classes except paladin and druid.
– Racials: rocket belt that allows players to activate one of two rocket abilities every two minutes – enables the player to jump up to 20 yards or shoots rockets at an enemy player within 30 yards; every 30 minutes the goblin can summon a pack hobgoblin, which will act as a personal servant granting bank access. Goblins also gain a bonus to their alchemy skill, and should a player decide to become an alchemist there will be an increased benefit from drinking health and mana potions. Additional passive goblin racials include a permanent 1% increase to attack and casting speed, and because of their knack for mercantile affairs, goblins will always receive the best possible gold discount regardless of reputation.
– Mount: Roadster
– Starting Zone: Lost Isles

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Other points of interest are:

3. Zone Changes/Additions
a. Old World
Leave what you knew of Azeroth behind, ladies and gents, for Deathwing has blasted a path of destruction through everything we once held dear!

– Many classic “Old World” zones have been remade; others have had their quests vastly streamlined (“The terrain is not guaranteed to change in every zone, many zones are likely going to stay the same terrain-wise but the questing will get the clean up.”)

– Thousand Needles gets flooded!

– Southshore has been destroyed by tsunami!

– The Barrens has been split in two; one area for high-level and one area for low-level characters. Portions of the Barrens have grown lush thanks to the work of the druid Naralex. The passage into Mulgore has been reinforced by the tauren, with high walls and a gate.; Camp Taurajo has been burned down by the Alliance. The Alliance are also setting up a base in the Barrens.

– Stonetalon Mountains: Eruptions decimate the landscape, spreading the flames of the Charred Vale even further. The goblins have cut through the mountains, forming a valley that leads into Ashenvale. This valley runs where the tunnel between Ashenvale and Stonetalon was. A mountain has also collapsed in the Charred Vale, allowing access to the sea.

– Darkshore is flooded, Auberdine destroyed. A new Night Elf town will appear to the north. Shatterspear Village, previously a closed zone, becomes an accessible subzone. New quest hubs will be added both north and south.

– Ashenvale: Zoram’gar Outpost is reinforced with black iron, similar to the Horde outposts in Northrend. Zoram Strand, therefore, is now a full-fledged outpost. Astranaar becomes the victim of air assaults launched by the Horde.

– Azshara: now a low-level zone for Horde players, directly linked to Orgrimmar via a path carved through the rear to the Goblin city; from the air it will look like a giant Horde symbol, carved by the Goblins; the goblin city there will also sport a giant cannon emplacement; The zone will be intended for players level 15 and up; expect to see a Goblin version of Mount Rushmore!

– Desolace: Once a barren wasteland, the Cataclysm has caused a rift to form, allowing water to flood in from the coast and bring life back to the region. However, the region is now being invaded by demons, including shivarra. A Night Elven camp will be added. New flight paths and new quest hubs will be added.

– Azeroth will change for all players, regardless of whether the expansion is purchased

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c. Hunters
– No more mana! Focus will be used instead, similar in function to energy. Rate of regen will be approx. 6 per second, increased with abilities, etc.; Maximum of 100 Focus

i. Warlocks
– Soul Shard system revamp! Will be a resource rather than an inventory item. The Shard Bar will appear below the character portrait with a max of 3 shards
– A new spell, Soul Burn, will be the only warlock ability to cost a soul shard (so far), and will empower most of your other spells to behave differently.
– Soul shards will regenerate quickly upon leaving combat, and you may also be able to use drain soul as a “soul shard evocation.”

4. Professions
a. Archaeology
– New Secondary Profession: Archaeology – lets you collect and use artifacts unearthed from the ancient races
– Each archaeologist uses the profession to uncover clues hidden in the world around them, such as troll relics or map fragments, and decipher their meaning, enabling the clever archaeologist to manipulate pieces of the past, learning the location of a treasure cache or valuable artifact. Such artifacts are highly sought after by the Archaeology Society, and they pay in gold and items for their return. Those who have mastered archaeology can find Titan artifacts, earning special currency used to unlock character paths and allowing the player to further customize their character. See Also: Path of the Titans
– Interacting with an artifact you find is similar to other gathering professions. It has been specifically stated that you will be able to track both Artifacts and your regular “tracking” for gathering professions.
– Recovered artifacts will be placed in a Journal, not in bags
– Rewards from Archaeology will be something “like”: a skeletal T-Rex non-combat pet or the ability to teleport to a dungeon you’ve been to before

b. Reforging
– allows Tailor to modify cloth gear, Leatherworkers to modify leather, etc.; Specifically, they can reduce a single statistic on applicable items and convert the lost points into another stat not already on the item; this service can also be provided to other players if you see fit

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8. Item Stat Changes – i.e. Integration
– Want to be more streamlined:
– MP5: This will be removed from items and replaced with Spirit. All healers will be given a meditation-like ability.
– Spell Power: Spell Power is being removed from items as well. Intellect will be improved so it provides mana and Spell Power.
– Attack Power: removing Attack Power from items. Agility will provide the necessary Attack Power for leather and mail wearers. Strength will provide the appropriate amount of Attack Power for plate wearers.
– Defense: The Defense statistic is also being removed from items. Tanks will receive the necessary anti-crit from talents, like Survival of the Fittest.
– Armor Penetration: It is being replaced with Mastery (see Mastery Section)
– Haste: Will increase the rate at which you gain energy, runes, and focus. Retribution paladins and Enhancement shaman will have a talent that allows them to take advantage of this benefit.
– Stamina: Players will notice more Stamina on gear as Defense, Spell Power, Attack Power and Armor Penetration are removed.

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d. Other
– Old PvP ranks are back
– New Arena maps will be added

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11. Guild Information
a. Guild Experience
– Players can earn guild experience through leveling, reputation ranks, boss kills, Battleground and Arena wins, and profession ranks. The top twenty earners from the guild per day will contribute to the guild experience total.
– With every acquired level, guilds will receive talent points that they can then spend towards their guild talent tree, which affects all guild members in the guild.
– Additionally, guild experience is converted into guild currency that can be used to purchase a wide variety of rewards, such as guild profession plans and reagents, vanity items, and talent respecs.
– Some Talents in the works include: “Penny Pincher” – reduced repair costs; Mass Resurrection; “Everybody’s Friend” – removes reagent cost for raid-wide buffs; “Cash Flow” – increases gold drop rate from creatures/players that give experience/honor; “Raid Summon” – summon the entire raid instantly

b. Guild Professions
– Guilds that use guild currency to purchase profession plans will be able to share any purchased plan with the rest of the guild via a vendor and skill trainer. Guilds are also able to create guild heirlooms; these items bind to the guild so that anyone in the guild will be able to acquire them. Just like the normal heirloom items, guild heirloom items will also scale with level and will support all armor and weapons.
– Guild members will also be able to take advantage of being able to create guild-specific versions of items that require fewer or different reagents. The new reagents are purchased from guild vendors via guild currency, and there will be support for all professions.
– Heirloom items for the guild are expected to encompass every slot.

c. New Guild Features
– Guilds will receive a special guild news-feed that will show them updates on happenings within the guild such as achievements, boss kills, etc. Guilds will also have access to profession info for their members and more. In addition to these features, guilds will also be able to acquire a percentage of gold looted on boss kills that will go directly to the guild bank. Additionally, guilds will be able to invite other guilds to events.
– Guild Tax System – will be available so that a certain portion of the gold looted by every member will go into the Guild Bank

d. Other
– New Guild Achievements
– New Looking for Guild interface similar in ease-of-use and utility to the Looking for Group interface

12. Miscellaneous
– There will most likely be an in-game event leading up to the release of Cataclysm
– “Battle.net will gain new features in the expansion, including an XBox-Livesque ability to see what your friends are playing and which servers they’re on, in addition to sending messages to them.”
– Dog Model finally spotted: a Mastiff in Gilneas, the starting zone of the Worgen
– System Requirements: yet to be determined – expect tweaks to the graphics at the very least
– Old World Achievement: There will be a number of current Achievements that will be removed come the reshape of Azeroth. For those of us that have achieved them, they will be moved under “Feats of Strength” and all points accumulated for them will be kept.
– Current heirloom items are not expected to be updated to support 80-85 and will remain for the 1-80 crowd.