Hmm... just replaced my programming PC with a tablet
My Christmas gift from my family this year was a Samsung Series 7 Slate. It's running Windows 8, Microsoft Office and Visual Studio. I use it for playing high end video games like DC Universe with a joystick. I use it for programming codecs used by nearly every broadcaster in Europe and the U.S. for contribution and I use it for watching films.
I have nearly replaced all my other PCs (except the ones hooked up to the projectors in my game room) with this tablet. I keep a dock at home and a dock at the office. In my backpack, I carry a 1kg computer a stylus and sometimes a joystick. The bag actually weighs more than the computer now.
So... while iOS and Android based tablets are pretty useless (have those too), this one is in fact a full PC replacement as it is in fact a full PC.
Somehow I see a whole lot of IT departments wanting to move in this direction in the future.