@exoteric: IMO, there would probably not much new thing on kernel level as driver writers are still busy updating their skill to support x64 and the new driver model.
On the other hand, I think Microsoft would experiment on different mix of UX elements in order to determine what will the next direction to evolve Windows.
IMO, adding touchscreen is just a start. People will probably want to go 3D. Kinect is a good start but not sensitive enough to precise movement. I'll imagine something like pairs of gloves plus glasses as display to create (mostly) virtual computing experience across office room, so people in a team can afford increased complexity in communication without significantly affecting communication efficiency. There will be a powerful server with BI tools, plus a few thin client workstations which has main purpose to provide UX to each users (I've not determined whether there should be thin application to do simple computing then send result to server, or just do all calculations and consolidations on server) .