preordered an iPhone 4S for AT&T already, can i have it activated on Verizon instead?

So here's the deal...I pre-ordered an iPhone 4S for AT&T from store.apple.com, and was planning on adding my wife onto my existing AT&T plan as a FamilyTalk add-on.

BUT, after some further research and thought, we want to have it activated on Verizon instead, since I don't think she'll tolerate the crappy AT&T reception that I get (or don't get, rather).

She is currently on Verizon (with a 5 year-old non-smartphone), and although the iPhone 4S she'll be getting in the mail was orginally purchased for use on AT&T, anyone know if it would be possible to activate it on Verizon instead? We could go through the process of returning the phone, but it seems kind of pointless if the phone hardware is no longer carrier-specific.

thanks