From Blizzard ( http://www.battle.net/forums/wow/thread.aspx?FN=wow-general&T=1469453&P=1&ReplyCount=169#post1469453)

"In searching through our records, we have determined that over 220 emails went out last night to Comcast users. Out of this group, only 61 people have not yet created their accounts.

I will be sending personal emails to these 61 people to insure that they have in fact received an email (we will resend their beta-signup emails if they have not).

Further, our support team has been working with other ISP issues all morning and are in the process of resending beta-acceptance letters that were bounced or rejected. This should clear up any concerns about your ISPs having been down last night for one reason or another.

As a last note, our emails are being sent out individually, and each email is unique. Because of this, ISP spam blockers should not be blocking them. However, your personal spam blocker might (this is the one that you have control over) so I urge you all once again to please allow emails from @blizzard.com to be accepted.

Thanks,

~Kat ;) "