Windows Phone Central forum user KoukiFC3S has managed to get a Lumia 920 running on the T-Mobile US network (reportedly making use of 1700MHz). Purchasing the developer unlocked device online, it was possible for a new account to be created with the carrier and the device to be used with some promising results.
Publishing a number of screenshots on our forums, KoukiFC3S was able achieve download speeds just shy of 9Mb/s. The Lumia 920 speed test supplied is shown on the left in the image below, while our own 3G speed test on the Three UK network is on the right (using a HTC 8X).
Should you be able to get your hands on an unlocked Lumia 920 and wish to make use of the handset on T-Mobile, there's hope at least. Be sure to join in the discussion on our forums by checking out the "I got a Lumia 920 on TMobile USA" thread.