T-Mobile is in the midst of some sort of LTE testing in and around Kansas City, according to a poster at XDA forums. These screenshots show an unlocked AT&T Galaxy Note (the original SGH I717 Note) using the T-Mobile network, and as you can see they suggest an LTE connection. While the first screenshot is familiar to us all, the second screenshot, the one of the device ServiceMode settings, is the one to focus on. It's a bit nerdy, but what you're seeing is a device on Band IV LTE (that's the 1700 and 2100 MHZ bands), on a 5x5 MHz configuration. The theoretical maximum of such a network would be 37 mbps download and 12 mbps upload. Worth noting, the poster clarified that he was using the standard T-Mobile APN setting, meaning that anyone in the vicinity with the correct hardware should see similar results.
It also shows speeds much slower than the current HSPA+ network many T-Mobile customers enjoy, but remember -- this is just a test. I imagine when we see a fully deployed 10x10Mhz LTE network from T-Mobile, things will be a good bit faster -- until people start using it. We'll keep an eye out for it, right along with you guys.