A good three and three quarter years after being announced at Blizzard's 2008 World Wide Invitational, Diablo III finally sees a release date of May 15th 2012. In conjunction with this announcement, the game is now also available for digital pre-orders from Battle.net, where you will also have the option of downloading an encrypted version the game ahead of release.
The list price of Diablo III's online pre-order is £44.99/$59.99, with UK e-tailer pricing typically being a more traditional £30-35. The Diablo III Collectors Edition has an MSRP of $99.99, and features:
[..] the full game on DVD-ROM, a behind-the-scenes Blu-ray/DVD two-disc set, the Diablo III soundtrack CD, a 208-page Art of Diablo III book, and a 4 GB USB soulstone (including full versions of Diablo II and Diablo II: Lord of Destruction®) and corresponding Diablo skull base, as well as exclusive in-game content for Diablo III, World of Warcraft®, and StarCraft® II: Wings of Liberty®.
Note also that gameplay takes place on Blizzard servers located near to your geographic region; there is no offline or LAN mode available for single player or multi-player content.
Blizzard's World of Warcraft Annual Pass, an offer which allows a WoW subscriber to commit to one year of subscriptions to gain in-game perks and a free copy of Diablo III, will also continue through to May 1st.
Source: Diablo III Blog, Press Release