I've been tracking the blogs on this one, as I am a tablet PC user.
From what I heard, the cost will be about $550 without the extra stuff (3G and TV tuner). It runs its own apps on top of XP, and it should have a 4-5 hour battery life. The bad news, the last demo had an internal battery.
Doubt it will be pressure sensitive for the price. Probably will have vectoring problems during inking like so many early tablet PCs - but for the size and weight, it might be a great alternative for the student. Keep scans of your textbooks, use the tablet note taking features (and/or type it in, depending on your courses), and carry only one small lightweight device in your bag. Even I find the TX2xxx series from HP to be a bit cumbersome (and noisy) at times.
Of course, what I am really waiting for is Plastic Logic's eReader with markup capabilities - too bad they're talking 2010 for release instead of this year. *sigh*