It looks like they borrowed the Apple's chiclet keys and frame, when he flips it over the PCB has Microsoft written over it [1]. To be fair for a prototype why wouldn't they use it, it looks nice and sleek, its flat and thin so sensors can be inserted between the gaps and more or less they had one lying around in their office.

[1] http://youtu.be/Y3dUeGNIX4M?t=1m14s