This seems very cool.
A Microsoft patent would seem to make an Xbox controller capable of identifying its user (and their profile) based solely on hand pressure, which apparently is quite unique to each individual.
The copy from the USPTO filing, as unearthed by Engadget:
A hand-held device having a body with a pressure-sensitive exterior surface. At least a portion of the pressure-sensitive exterior surface is designed to be grasped by a user's hand. The pressure-sensitive surface contains a plurality of pressure sensors operative to provide an output signal proportional to a pressure applied by the user's hands to the exterior surface of the hand-held device at the area the pressure sensor is located. The device also includes a memory for storing the output signals provided by the plurality of pressure sensors and a processor for comparing the output signals provided by the plurality of pressure sensors against stored pressure profile signatures for positively identifying the user.Translated, it seems the controller would be designed to recognize which player is using the controller and could tailor the game experience accordingly.
Engadget: Microsoft patent details pressure-sensitive Xbox controller for storing players' profiles
this can't be for the CURRENT xbox can it :S