I don't know where the Ipad fits in either. I think Apple have gone overboard as I can't see myself buying one.
The I-Phone does everything the Ipad does, but is much smaller, is more convenient when on the road, other than a proper or miniature laptop that is.
But then again, Apple has had many sales for the Ipad already, so it is a money spinner for them!!
It is far too expensive for what it is. If the pricing isn't reduced, then I can't see the Ipad survive in the longer term.
I would still prefer purchasing a book than download an Ebook from Itunes and paying for it.