Tried to activate my phone last night with no success. Woke up a bit early and called AT&T. They told me everything was fine on their end and to call Apple. I figured I'd just swing by one of the Apple stores in Manhattan, so that's what I did. They told me it was AT&T's problem. While walking to work, I swung by an AT&T store and they used a nice hack to get my iPhone activated. Now it's all gravy.