GAH! The iPhone Isn't CDMA
Short answer: No. The two carriers use an entirely different kind of network technology, the phones aren't transferable between the networks.
Potentially, Apple could build an open iPhone that works on Verizon's CDMA network. I don't how that would sit with AT&T though, the operator has exclusive rights to support the Apple phone in the U.S. at present.
— Dan Jones, Site Editor, Unstrung