We are developing on the tablet PC so there are a few floating around the office. I got to test drive one for a while, and I must say that that for a geek toy they have a very high "wife acceptance factor". Apart from that, I don't see it replacing my "real" laptop anytime soon. There still isn't any killer app for tablets (maybe OneNote will change that), they don't have the specs for heavy-duty usage (such as development), and their price-performance ratio is still outrageous.
I'm confident that the third generation or so of the tablet PCs will rock, but as of today it isn't much more than a waaaaay cool gadget.
My 2 cents :)