I think the idea of Apple releasing a tablet is credible, despite Steve Jobs decrying the idea.
The problems he cites is that handwriting is slower than typing, which is correct. But for checking email and listening to streamed muzak, it makes sense.
But I think if Apple do go for the tablet, they're going to squeeze all of the utility they can out of it.
For instance, IT guys are using the iPod to copy disk images across Xserves.
What if Apple made a consumer version of the tablet, plus an enterprise version that run a modified copy of Apple Remote Desktop [or something like that] that works over this new, faster wireless standard I've been hearing about recently.
Imagine walking round the office / lab / classroom administrating a bunch of iMac's, eMac's, G5's, iBook's and Xserves.
Suddenly you have a device that cuts a swathe through work _and_ play...