Jonathan Geller reporting for the Boy Genius Report:

That’s right, you’re looking at photos of an iPhone prototype with T-Mobile USA 3G bands. The actual internal model is N94, and if you remember, the Verizon model is N92 while the standard GSM variant is N90. We have verified that the phone itself is running a test version of Apple’s iOS […] and it includes internal Apple test apps like Radar and Apple’s employee directory app.

There’s no way of knowing when or if the iPhone is actually coming to T-Mobile anytime soon. But if AT&T does manage to acquire T-Mobile, the iPhone will be coming to the carrier eventually.