While AT&T says 7.2Mbps is as fast as their 3G service will go before they roll out 4G, T-Mobile began rolling out HSPA+ 3G service in Philadelphia at the insane speeds of 21Mbps, ahead of their 2010 predictions.
Though as John said, this HSPA+ is a stopgap and may leave T-Mobile in the dust when the other carriers migrate to LTE, it's definitely the fastest speed around at the moment. On a personal note, it's good to see my hometown in the news for something other than Michael Vick, but having moved out west I can't test how accurate those numbers really are. Any Philadelphians want to bust out their T-Mobile handsets and see what HSPA+ can do? [Boy Genius Report]