Hi Brad--
I think a true Dynabook is long over due. Today's hardware doesn't suffice. Either it's too underpowered, or too bloated. Too small, or too heavy. (and all too expensive!)
What do you have in mind? How fast, how big, how heavy, how much? Personally, I think something even as mundane as a Powerbook is adequate; certainly more appealing than the old Dynabook mockups.
-C