The tablet computer is a dead market. It's not happening, period.
But something else is coming...
Yep, a
touch tablet.
I can see dozens of dozens of applications where this would be used where a laptop or desktop or even iPhone isn't suitable.
Doctors, nurses, walking around with it to input or check patient data on the go which ties to a central server or network. Retailers (stores, outdoor nurseries etc) checking inventory. Linesmen. Teachers. Journalists. Police. Heck, even waiters tapping in food and drink orders.
Mount it in a car and straight away you put all the current single-purpose in-car (video, GPS etc) systems on the back foot like the iPhone did with regular mobiles.
Basically,
every single place where a computer can be held in one hand like a notepad while standing up and walking around. There is not a single fully-featured product currently filling that vast market right now.
True mobile computing. Laptops just don't cut it for that role - laptops are 'mobile' but they are not mobile computing in the true sense, ie you have to sit down to use one or hold it awkwardly if standing up. Smart phones are just too small. Couriers use basic Newton-style devices to collect signatures etc, but it's no potential Apple iPad.
Thinking of it as just a larger iPhone/iPod game or video player or ebook reader is very limiting imagination in regards to the hundreds if not thousands of potential uses for it, where there is no current competition for it. But there will be once its released once everyone else realises and starts copying it, it'll be a whole new category of computing.