I really don't want to piss anyone off, but I know I'm going to by saying this. Seriously, after I got to the last set up screen and I picked my plan and everything, it said activating. Then I looked at my phone and it said activating. Then I turned my head, and looked up at the computer and looked back and the iPhone said, activation complete or whatever. Then I removed it from the dock and it started vibrating, and I realized that I had a text message. I picked up my old phone and tried to call and it said unregistered sim. It literally took 30 seconds to activate.
I am under the impression that it is NOT the service provider switching, the porting of an old number, or the region of the country that we live in that is causing this.
My brother and I waited in the same line. Got the iPhone one right after the other. Set it up at the same time (him on a PC desktop, me on a Mac). His got activated-synced-the works. Mine is still waiting for activation from this wonderful mysterious email.
For all the folks that haven't activated yet and are porting numbers...blame your old carrier.
My phone activated in about 5 minutes. I had to power it off and back on for it to take effect though. Full power off...Hold down the power button and then slide across to power off. When you turn the phone back on you'll see the Apple logo again and then wha-la!