What I would want, but know I will probably not get, is openness. Installing Apps from anywhere, and not just the iSlate App Store (or whatever they will call it).
I'd like to be able to link several devices, through whatever high-speed wireless connection to enable a shared environment. Be it among friends to play games, family to watch a film or one (or even several offices) to collaborate in a meeting.
What about not having that physical display port, but a separate device you can connect to a beamer which connects wireless to your tablet.
Now, battery life. Has to be great. We already know the Kinetic watches, which are charged by the movement of the one who wears them. These tablets will also move a lot, can I hope for battery life extended by movements? Combine that with solar energy, and we can use them for a whole day without any worries.
Hmm, now - what if they'd charge in the same way as many shavers do. I forgot what it's called, but something completely without wires. Perhaps the iSlate could even be completely water-proof.
Anyway, it will probably not be much more than just a A4 sized iPhone - as others have been expecting.