It's almost inconceivable that Diablo III is coming less than a month away on May 15th. To put the servers through their paces, Blizzard is opening up the beta of the game to everyone with a Battle.net account. You'll also need to create a "BattleTag" which seems similar to an Xbox Live gamer tag.
The open period of the beta is only open for a short window. Friday, April 20 at 12:01 p.m. PDT (noon), until Monday, April 23 at 10:00 a.m. PDT is all the time you'll have before the game ships. Blizzard has the game client already available for Mac and PC. Will this be the first Diablo game for anyone else?