Blizzard will send out 275,000 Diablo III beta invites to opt-in testers, so make sure to double-check your Battle.net Account Management page, and run the tool to submit non-personal computer information if you have upgraded recently, or upgraded your NVIDIA/ATI drivers. Additionally, create a BattleTag which is required to play Diablo III beta.
Did you lose all hope? Blizzard once more takes players by surprise with a massive Diablo III beta invite.
We’re in the process of sending out 275,000 Diablo III beta invites to our opt-in testers. As it’ll take us a while to notify all the lucky invitees, we recommend heading to your Battle.net Account Management and seeing if you’ve received a Diablo III beta license. If you have, you’re good to go!
Download the beta client and use your Battle.net account and password to log in once it’s installed. While you’re logged into your Account Management page though, don’t forget to create your BattleTag. You can choose this permanent account-wide nickname by clicking on the BattleTag “Create one now” link on the left side of your main Battle.net Account page. Choose wisely as there’s no current ability to change it. A BattleTag is required to play Diablo III, and so whether you get into beta or not you should pick one while you’re there.
Keep in mind that with such a large amount of invites for our test hardware we fully expect a strong possibility of stress test issues, such as an inability to log in, disconnections, and potential lag/latency. We’ll also be testing our queuing system ,which you may see when attempting to enter a game.
Thank you for your continued help, feedback, and patience as we approach the May 15 release. — source