We've seen a few wacky split keyboards in our day, and even the occasional back-typing peripheral, but Microsoft Research has just congealed the core ideas into a why-didn't-I-think-of-that device for mobile use. Dubbed RearType, the QWERTY solution literally sticks a three-row keyboard on the back of a tablet PC, allowing users to have the same physical sensation as on laptop or desktop without taking up valuable touchscreen real estate. While there's still a few kinks to be worked out of the system (like how to set it down without triggering input) and no plans yet for commercial availability, a brief study showed users could attain 15WPM speeds on average with a single hour of training, and one participant managed to eke out a healthy 47WPM in the same timeframe. We imagine a certain Motorola device is feeling a mite jealous right about now. See the front of the (non-Microsoft) tablet right after the break, and read the full study at our more coverage link.