Re: Actual use?
I think the main market is consumers, but not to say there won't be business applications too. Things like looking up recipes in the kitchen, watching a movie on a plane, keeping kids occupied in the back of car, reading your favourite blogs in bed before you go to sleep, the whole ebook thing.
Sure, you and I know there are plenty of other devices that can already do some or all of these things, but Apple's expertise is knowing how to package it all up and deliver a highly desirable and well designed consumer appliance, not just a piece of geek technology that ticks a lot of boxes on a spec sheet. I suspect the iPad is going to be phenomenally successful therefore.