
Blizzard have unloaded a huge number of Diablo III beta keys to North American Battle.net accounts. If you have one and have done the the beta opt-in be sure to check your profile - you might be lucky.
Blizzard also warn their community that with this huge giveaway of keys it is likely for an increase in phishing attempts to be seen as well. The easiest way to avoid it is, of course, bypass all e-mails and directly go to your Battle.net account - should you have received access, the Diablo III beta icon will be active. If you're not on the NA server don't despair - in the blue post announcement, Blizzard are promising more giveaways as well as regional betas.

Links
Battle.net - Source