If you want 2.2 either root it and install it or sell your phone and buy a newer version phone. I have given up on T-Mobile updating it. I had rooted mine and installed 2.2 but went back to 2.1update1 because I didn't like 2.2. You may like 2.2, I honestly didn't because I liked the HTC sense look and feel. Without it, it is very boring. The only redeeming factor was saving apps to SD card and most you couldn't run if they were saved to SD card.
So i'm waiting for the official update. Hopefully it's better, if not, i am selling and either going back to iPhone or preferably buying a Nexus S.