If so, you've probably heard about the upcoming expansion, Cataclysm. Info, at least officially, is kind of scarce. Luckily there are websites that have a bunch of info leaked from the current alpha of the game. Either by people actually in the alpha or just running the leaked client.
One of the better sources of leaked info I've found is the forums on MMOwned. For some footage it shouldn't take long finding some on Youtube. The standard spoiler warnings apply and all that.
And now for a Cataclysm trailer that's slightly less official than the official one but still pretty amusing.
Edit: Looks like the closed beta for Cataclysm has begun. The NDA has been lifted and therefor you shouldn't need any "leak" sites for info now. Woo!