After about an hour of awaiting activation (actually transfer of service from 3G to 3GS), I called AT&T. The AT&T rep was clearly clueless and wanted to blame "iTunes."
I told her I needed her to "push through my activation" and she was able to do something in their system that, after I shut down and restarted my phone, resulted in immediate service activation.
Hope this helps anyone in similar straits.
yes -- this is what they can do. The AT&T guy that helped me at the store yesterday said for if some reason it didn't activate to come back and he would "force" the activation, but they only do it in extreme cases.
It worked just fine for me though - activated and placing and receiving calls and voicemail set up all within 30 minutes of taking it out of the box.