You always hear rumors about the Iphone coming to Verizon. Why not the Iphone on T-Mobile? Say what you will about T-Mobile's coverage area; I think their customer service is great. To me that counts for something.
T-mobile (specifically one of the many Deutsche Telekom companies) is one of five or six major multi-national carriers with iPhone worldwide, just not in the US. Fortunately or not, I have ATT coverage.