I think T-Mobile has something up their sleeves, but knowing how T-Mobile operates, they will wait til Q3, to launch a nice device. It will most likely have HSPA+. Also, last year when AT&T launched the iPhone 3GS, all T-Mobile could show for was the MyTouch 3G, and the supposedly high end Touch Pro2.
T-Mobile needs to be talking to Apple, to be a supported iPhone 4th Generation carrier. Heck, if the rumors about Verizon getting an iPhone, which as of right now are rumors, then T-Mobile show nuff needs an iPhone. They are the next logical GSM nationwide carrier in the USA.
Even if T-Mobile is running AWS, Apple can add T-Mobile's 3G band, but its either AT&T asking Apple not to, or that Apple is really retarded, and can't figure out how to add 850/1900/AWS/2100 to one single chip.