Blizzard still doesn't have an official release date or window for Diablo III, but after kicking off internal testing on the game last week, it does have an idea of when it will begin external beta testing.
The beta is set to begin sometime in Q3. That means we'll be seeing it between July 1 and September 30 of this year, assuming Blizzard hits its current target which is subject to change.
A 2011 release for the full game is still a possibility, and Blizzard is striving to make that happen, but as per the usual, it won't sacrifice the game's quality in order to hit a certain release date.
Blizzard recently suggested the game was in the "home stretch."