If you don't know by now, Google have been working on a new Operating System based around their Chrome Web Browser. That operating system (in source code) is now available here:
http://www.chromium.org/chromium-os
Here's an intro video explaining Chromium
A more in-depth demo (Interesting to MR users might be the hint at 6:35 at how Google is portraying Google Books usage in relation to the netbook)