Diablo 3?
http://www.diablofans.com/ and others are saying that it might be a teaser for Diablo 3. There is a Blizzard event this weekend where they are expected to announce the release date for StarCraft 2 and maybe even the making of Diablo III.
Personally, I think it looks like a Protoss Archon from StarCraft, but only time will tell.
Thoughts?