Weird price point
I don't believe that Apple will do anything like a full OSX tablet without pricing in line with other Macs. That's £1,600/$2,000 at least... At that price I doubt they'll sell many more than the PC manufacturers have.
Anyway for that money I could have the Motion Computing J3400 - which is as close to the classic HP/Compaq tablet that I can find. Everything else is too heavy, as the manufacturers all now insist on a fixed keyboard, taking the weight into the 1.5kg range, rather than under a kilo, which is a lot more comfortable to hold for long periods. My current HP tx2000 was £650 and is a full (if slow) PC, but I'd ditch it in a heartbeat for something of a similar price where I can take the keyboard off.
Another option is the Always Innovating touchbook. Now finally shipping, but the software is still in beta.* $300 with detachable keyboard, linux, lots of battery life, $200 without keyboard.
A giant iPod Touch with a bit more of an advanced OS, access to the iStore, a decent browser, and the alternative of a stylus for handwriting recognition would be wonderful. Who's really going to use a tablet for anything other than reading, internet, diary/addresses and the odd short note? Not many, and they can get what they want for sufficient cash. GPS would be very nice to have as well. Plus USB for 3G dongles.
However, $800 seems a bit steep for a big iPod Touch, given it's limitations. Something like that at $500-$600 would be wonderful. For $800 I'd want all the bells and whistles above. Come on Apple, my credit card is waiting.
* Dear Reg Hardware, please, please, please can we have a review of the Touchbook, as this could be brilliant, or a horrible flop - and I'd love to be told rather than shell out the cash and find out the hard way.