A quick search on the internet gave me the following link:
http://news.cnet.com/8301-17938_105-9686982-1.html
This is a device of which the concept is what I am more or less looking for.
But replace one screen with e-ink, for less enery consumption and provide a way to operate on an e-book aswell as full blown PC level and we are set.
If you need a keyboard use it in landscape mode and lay way screen flat on your desk and use it as a keyboard (you would loose the tactile feel I guess, but an e-ink screen would be especially usefull. The screen doesn't need to change, unless you would want it to, in case of pressing, shift, alt, alt-gr, ...
So only the touch interface would require powering but not the screen as it can stay (mostly) still.
Edit: Also have a look at this site:
http://www.estari.com/
Check out the Canova, replace one screen of it with e-ink, and your already half way where I want my design to go to.
Cavelion