If you attended Blizzcon 2007 or the Worldwide Invitational 2008, chances of you having a beta key sitting in your inbox right now is pretty likely.
Keep in mind, you may not have one though. Blizzard has made it pretty clear that having those doesn't guarantee you a spot right now, that it just guarantees you a spot sometime. However, from reports I've gotten from people who have attended the events - not a single one has NOT gotten theirs yet. So chances look pretty good that if you attended, got the beta key entered like Blizzard told you to do soon, then you're in.
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Keep in mind, you may not have one though. Blizzard has made it pretty clear that having those doesn't guarantee you a spot right now, that it just guarantees you a spot sometime. However, from reports I've gotten from people who have attended the events - not a single one has NOT gotten theirs yet. So chances look pretty good that if you attended, got the beta key entered like Blizzard told you to do soon, then you're in.
More...