The dock is a pretty good bonus for those looking to use one of these in car. I like the touchscreen and swivel display. I'd go with Windows XP Tablet over Vista. An 800MHz proc running Vista would be rather slow. It's smaller than my Lifebook P1120, but not small enough to be more portable really. ~2 inches less of width doesn't make it fit better in my bag. The keyboard would be on the very edge of touch-typing capability.
If the Asus EEE comes out, I'd go with that instead, as I'm not inclined to spend that much on a laptop. However, if the EEE, as well as the Nanobook, doesn't come out, I might grab this Lifebook.