You know there is more than one version of the iPhone on sale right now. As for the iPhone being sold only on AT&T, well that was Apple's decision wasn't it? They tried to impose intolerable conditions on Verizon to start off with, so Verizon refused to bite.
Revisionist history Smokingjoe! Apple offered the iPhone first to Verizon. Verizon wanted to make all of the iPhone features available ala carte. You want Internet? That's extra? Visual voice mail? Extra! iTunes? Extra charge! Email? Extra! Notepad app? Buy it from Verizon. And they refused to upgrade their system to what was necessary to handle the iPhone.
AT&T agreed to an all in one price for everything and agreed to spend the money to upgrade their system.