I sit here, in my office, typing this post on an iPad. Not quite the same as a computer, but not too bad for my typing style and speed. A little slower, and the extra keys like numbers and symbols aren't exactly where I'd like them to be. We got one last year to test them for labs and lectures. It's still "not quite there yet"as far as using it seamlessly in the classroom, but I think the newest version announced today gets these things a little closer to the mark.
What I'd really like is a tablet that has all my geologic maps loaded up so I can add map data in the field, draft strat columns and make field sketches. Although I would have a hard time giving up my write-in-the-rain pen and paper system.