I’ve seen a lot of complaints about wait times for iPhone activation. Ben Brooks was told by AT&T that his iPhone’s activation would take place an hour after he called them, and that’s likely after waiting a bit of time before calling AT&T and spending some time waiting to talk to an actual person on the phone.
I didn’t have any problem activating my iPhone 4S. I plugged it into iTunes to restore from backup and activated online. After the device’s initial sync I rebooted it and it was activated and ready to use.