Yeah, I don't expect a World of Diablo... I mean, they own the MMO market already, so.
Anyway, some potential "proof" from 4chan's /v/ board:
Evidence for it being Diablo 3:
- Two runes appear in the ice, one may be the Shael rune, may not be. The other is indisputably the Hel rune.
- the WWI falls on the 8 year anniversary of Diablo 2.
- It's been leaked that Blizzard is announcing a NEW GAME.
- TWO unnamed secret projects have been in the works for a long time. One is an MMO, one is not.
- The numbers of the two 'secret' images revealed so far correspond with letters in the name "DIABLO". 04.jpg = D, 15.jpg = O.
- An image from the 2008 European WWI site shows Diablo standing front and center, above Arthas and Kerrigan.
- Blizzard has only done elaborate, slow splash page teaser reveals for NEW GAMES, not expansions that have been well-known about for a year.
- Blizzard loves to fuck with people. The splash page for the WoW announcement was SPACE themed.
- The Splash page appears on not just worldofwarcraft.com, but also blizzard.com, battle.net, and diablo.com
- Blizzard only just acquired Diablo3.com a little over a month ago, despite having all of 8+ years to do so until now.
- The Purple Walrus pic is the trademark of artist Michael Dashow who did the majority of the models and animations for Diablo 2.
And a nice montage of related pics (Although the purple Diablo looks a bit shifty):
Mind you... It's still all speculative. :P
I am eagerly looking forward to checking the splash page tomorrow to see if it's been updated again. I mean, that crack at the center grew quite a bit today, so...