Personally, I'm not sure if I'd prefer one.
I think the thrust of these is as a media viewer but I'm certain that there are significant productivity applications that could be developed.
I was recently in a doctor's office that used what I know to be very expensive tablet/laptop machines as the primary interface for the nurses and doctors to do their record keeping. Not that the mac tablet would necessarily be the solution but cheaper, lighter, keyboardless, wifi driven, is where they are inevitably going.
I have little doubt that, if Jobs is going to pitch it next month, we won't come away from that with a firm idea of its role in the marketplace.