Roommate and I (both Verizon customers) activated ours around 7:00PM ET Friday and it only took ~3 minutes each. We both got new AT&T numbers -- no porting.
My partner (T-Mobile customer) activated his about an hour later, again with no porting. His activation timed-out in iTunes, telling him to wait for an email. He got the "your iPhone is activated" email about 5 minutes later.