I have an Apple iPhone 3gs 16gb for sale. Unlocked running version 5.1.1 on T-Mobile at this time. I think when I reset it, it will need to be unlocked again. Asking $120.
Not sure, but they sell the iPhone 5 now for $600+. This one runs the same iOS. They do support them.
Just called, they don't unlock for you. You can take it to AT&T and have them unlock it. Or do it how everyone else does it...
If the phone is unlocked, all you have to do is sync your contacts with Outlook. Move SIM to iPhone, sync iTunes with Outlook. Done.