> bonus points for something like ultravnc support so it can just be an extension of your desktop display.

I'm waiting for the day when just setting two tablet-like devices near one another makes them into one, larger screen. They could even snap into one another to form one huge, seamless slab. Of course, you'd need something a little more advanced than even remote X server/client sessions to get it to work, because someone might want to "tear off" an application in one corner and take it with them to the bathroom, behind a lead wall for some reason.