I think with AT&T's systems it says back-ordered by default in the beginning. You don't technically have a phone yet. A phone is delivered from China to AT&T (in a box with several others), unpacked and then it's assigned to a customer and shipped. AT&T probably doesn't even have any phones at this point.
I don't know if this is current, but it's the UPS planes that leave Shenzhen headed for staging in the U.S. Considering that next week is launch, these could be the phones that will get delivered that day.
http://flightaware.com/live/iphone
Thanks, it changed to In Progress--