Google Chrome OS is Linux. Not. (Here comes applinuxes?)
fwd2tweet.com
fwd2tweet.com
Just move the tab bar at the botton, Bookmarks button in place of "Start Menu" and you have nearly got yourself a complete desktop. New windows with multiple tabs can act like multiple desktop features of Gnome/KDE.
If nothing else, it would be an interesting experiment, I frankly do not see any reason it can't be done by someone who knows enough of linux startup scripts, and desktop environments.
Call me back in 2010 or whenever GCOS arrives on the market, and I'll compare it to then-current Moblin and Linux distros and Microsoft Windows for the netbooks.
(And GCOS? Wasn't that an OS from GE? Fifty years ago?)