As far as portable tablets go, I am waiting on the Asus Eee PC T101H, but I have no idea when it will be out. The Gigabyte M912 tablet is already available, but I haven't had a chance to try one out. There's also the Lenovo Thinkpad X61t and X200t as well, but they're a bit bigger.
I will try the new Kindle and see if it will be an adequate substitute for a while. I think the notes are stored in a text file, so they should be able to be transferred to another computer.