Microsoft has just patented what looks like the next generation of fingerprint recognition with pressure sensors.
I have no idea how something like that would work, but Microsoft seems to have some clue, patenting "personalization using a hand-pressure signature" on an Xbox 360 controller.
It would seem that the controller would be able to detect the user based on his or her hand pressure patterns.
Chances are, like the Kinect's recognition software, it probably won't work half the time. As nice as this technology may be, it'd be nice if they stopped with the gimmicks and got on with the business of making videogames.