Just while we're on the subject, can I push a slight tangent?

What about prepaid? I'm looking to come to next T-Con (or one after) and I have an unlocked 3G Triband handset. Where would be my best place to start investigating prepaid services while I'm in the states?

We have 4 companies here, and they do all across Australia without any roaming charges or anything like that, but I can gather its not the same on the US? Is it dependent on state to state?