uh, lol @ all the wotlk comments? why would they make such a big deal about it going into beta? iirc, they didn't with tbc. my guess goes to d3. i'm assuming the graphic will change over the days like sc2 did, so i'm expecting the ice to gradually melt away to reveal a gateway to hell or something like that. also, in last months pc gamer, the blurb for next months issue was about an announcement of a huge game, and a quote from it is "this news is so big, we had to go to ***** to get it" aka "... we had to go to hell to get it". inc d3.
edit: also, ice would be way too obvious for wotlk, i mean come on... blizz is a lot more creative than that. they probably wanted everyone to think it was something wotlk-related so it would be more of a surprise in the end.