Secondary profession: Archeology (researching ruins give artifacts, used in Path of Titans questline)
Has a sort of puzzle minigame to discover what artifact it is. Artifacts can be sold for rewards like recipes, items and gold.

Deathwing has returned (is main boss of Cataclysm)

Path of titans questline (has multiple paths) and together with Archeology will grant extra glyph slots

Alliance gets Worgen Horde gets Goblins

New Class / Race combinations

Flyable mounts in azeroth

Kalimdor and Eastern Kingdoms revamped

Guild leveling system

Heroic version of Deadmines and Shadowfang Keep

Rated battlegrounds (will grant rewards same awards as arena)

Path of the Titans questline

Lich King is still alive

Goblins get roadsters as mounts

Goblin racial: rocket belt (reverse disengage) , Worgen Racial: Darkflight (sprint)

Seven new zones

Sunken City of Vashj'ir will be an underwater zone (with 2 dungeons)

Worgen/Goblin do start at level 1

There will be underwater cities

Still 51 talent point trees but 5 extra talent points and talent mastery system

Cheaper repairs and mass resurrection (rezzing entire raid after whipe)

Guild leveling system (20 levels) will provide higher level guilds with perks and guild talent trees, more info on this later at another Blizzcon Panel
Raids, dailies, battlegrounds all grant a guild experience

All major cities reconstructed for flying mounts

Underwater mounts; will be like flying mounts with normal flying speed

Deepholme with be the center zone of the expansion with teleports to other zones, also it is the largest zone.

Attack power, MP5, defence, block value and spell power is gone, comes from other stats and talents now. Armor penetration is gone completely
Stamina is going to more equal across gear

Hunters don't use mana anymore, but focus
Focus regenerates contunously, Steady shot improves the rate of getting focus bag.
Rogue energy comes back at a 10 / sec rate, Hunter focus comes back at 6/sec (12/sec with steady shot)
A shot costs 30 to 60 focus.

Tol barad world PvP zone, island prison off the coast of Eastern Kingdoms. (Wintergrasp and Quel'danas combined)
Battle for Gilneas battleground, streetfighting to capture various districts

Worgen walk around as humans, shapeshift into worgen-form for fights

Cataclysm will change the ways abilities are learned. Abilities ranks are gone and ability will just scale progressively with levels instead.

Multi-passenger flying mounts could be added in the future. They might also allow crafters to craft 310% flying mounts if they already completed an achievement rewarding one.

Shadowmourne - You won't get Frostmourne in Icecrown but Death Knights and Hunters will get a Legendary Axe named Shadowmourne.

Warlock soul shards are no longer stored in bags, less abilities use soul shards, will be integrated in user interface and will function more like DK runes

PvP titles coming back as rewards of rated BG's

Proffesion cap will be raised to 525 new title will be Illustrious.

At first i thought the new xpac was gonna be a pile of dump but after looking at the trailer. (which is EPIXX btw) and reading through the blizzcon panels and this i say its gonna be pretty pro.

I have no idea as to how much cocaine you ingest, but as far as I'm concerned, that expansion is going to ruin this game. They're making it so easy that its stupid. I play this game because in order to get far, you need to have an IQ higher than that of your shoe size. All this expansion is going to do is make this a casual's game.

Has its ups and downs....