Blizzard Entertainment has at long (looooooooong) last confirmed an official release date for its currently-in-beta lootfest RPG, Diablo 3: May 15, 2012. The news is currently the first thing you see when you head over to Battle.net, with a giant image of the box situated above the release date as well as a link to a pre-order page.
Note that you'll need a Battle.net account to proceed into the pre-order page. Only the $59.99 digital version of Diablo 3 is currently available for pre-order through Battle.net, though a same-priced boxed release and $99.99 Collector's Edition will also be available. Those haven't yet been added to the official Blizzard Store, but it's a safe bet that they soon will be.