European Beta keys started rolling out beginning at 6AM. I don't know about you but I will be anxiously checking my mail box when I wake up in the morning (that is if I make it to bed at all). My guess is that we will see North American beta keys at about 6 Pacific time (9 Eastern). For you folks staying up all night with us, that's in about 4 hours.
The crew here at WoW Insider is biting their nails in anticipation of bringing the latest breaking news on the expansion. We've discussed why we should be in the beta, now we'll see who wins the lottery. My understanding is that the Beta will be a ramp up, so do not lose hope if you don't get your email right away. There will likely be much time for testing.