It uses X11, gdk-2.0 and clutter-1.0 for drawing, and gtk-2.0 widgets. All from your Ubuntu system on which you would build an image.<p>So, it us just a layer on top of Ubuntu's "core" (glibc, X11, gtk, dpkg) with custom kernel, pam_google (!) desktop manager, window manager, installer and updater.<p><i>Good coders code, great - reuse.</i> This seems like Google's favorite mantra.<p>update: <a href="http://src.chromium.org/cgi-bin/gitweb.cgi?p=chromiumos.git;a=blob_plain;f=src/platform/init/preload-chrome.conf;hb=HEAD" rel="nofollow">http://src.chromium.org/cgi-bin/gitweb.cgi?p=chromiumos.git;...</a> - to those who understands =)