Welcome to Player Attack!
...with a little help from open source software, a NES emulator, and a little ingenuity. The same guy who created the Kinect lightsaber has now set up the motion-controlled peripheral with a copy of Super Mario Bros., and the results are pretty awesome, if a little clumsy.
I could have placed a simulated keypad right in front of me that I can press with my hands, but I thought full body gestures were more in the spirit of Kinect.
Of course, Mario isn't designed to be played like this, so this is really really hard.
YouTube user yankeyan explains he's been working on the project as his own tribute to the game's 25th anniversary. He describes it as a "proof of concept", rather than necessarily a workable prototype. It uses OpenKinect software to get the peripheral to communicate with his PC, which is running a simple NES emulator.
Obviously, it still needs work, with a few sensitivity issues needing to be ironed out, and the game made a little more smooth overall. But, once that's done, there's nothing stopping Kinect from running side-scrolling platformers and giving you a bit of a workout at the same time!