The idea is actually something I've seen punted around before. Have chrome OS for that near instant-on easy to just hand off to family or whoever and have ubuntu (or your flavor of choice, I pick Ubuntu mostly because there's already an install script for it on the Cr-48.) for those times when a full desktop is needed. I like this idea because you don't really sacrifice anything if you have the two hooked together right and the system's drive(s) mapped correct.y. After all if both installs use a third partition (or dedicated drive) for the home directory (think 'documents and settings' directory for you windows folks) You don't even have the hassle of duplicating data between setups.
Oh I'm sure it's far more complicated, but if you have a google account chrome/chromium synchs data so all the browser specifics would be intact. The self-contained home/user directory would be purely for download/non-syncable items you want carried between sessions.
Now that my mind's looking at this I have to wonder if, since currently the install of Ubuntu I have is using the chrome OS kernel, if you can have that as standard (have Ubuntu/chromium/whatever gets installed second use the kernel of what's already there if a linux is installed.)
Thoughts anybody? I'm somewhat a power user, but I'm not all that deep in the technical bits. How hard would that setup be?