With the advent of iPhone 3GS, people have begin to rumor about the next iphone. Some call it as iPhone 4G. here is a relevant video about iphone 4G.

While anything is possible, it is unlikely that Apple would release the iPhone 4G when it would only be possible to be used within 25 markets within the first year, or 1/3 of the US population assuming that they go solely for the largest population centers. This would be a difficult sell for hardware that is directly incompatible with other networks due to different frequency spectrums and packet encapsulations.

While it is possible that Apple could segment the market to release a 4G and a 3GS - Mark 2, it would be much more likely that Apple would want to start providing iPhones to other carriers first and then plan on the 4G for 2011 when Verizon is claiming they should reach 80% coverage of the continental United States.

~Adrian