The one thing I've always thought was a major barrier with MMOs is the fact that ultimately, no matter how many quests you do in the name of your faction, the game-world itself simply does not change - there's no definitive outcome for your actions barring levlelling up and collecting loot.

Thankfully Blizzard have seen this, and given the reach of the World of WarCraft brand and the number of subscribers they have, they've finally gone and drastically altered the game-world.

To see exactly what I'm talking about check out the full World of WarCraft: Cataclysm trailer here. You can also have a look at a host of screens here, and our game page here.