It may be old technology (oh so last week...) but I have been lent a Compaq tablet PC and I'm really enjoying it. In form factor it is the size of a text book. With a touch of a button, I can orient the screen from horizontal to vertical. It only weighs 3 pounds. What I love about it is that I can use it as an e book reader and be cozy with it in places where my laptop is clunky. And it helps to be able to handwrite when I'm working on edits. The handwriting recognition is about 90% accurate-- which is pretty amazing if you know my handwriting.
what makes the tablet problematic in terms of replacing my laptop is the slow processor speed and small hard drive.
It's definitely not a laptop or desktop replacement, but it will certainly lighten the load when I travel and if I can load it up with lots of ebooks, I have a library in my hands.
It also has an optional keyboard that I'm looking to pick up on ebay.
I have been lusting over an ebook reader and have been impressed by the digital ink technology of the Sony reader and the kindle, but for now, the tablet will fit the bill.
Oh--and it also supports voice dictation. Something I've always wanted to play with.