Google today released a preview of the Google Chrome OS…
I don’t have much to say at this point, except that I’ll probably do a review of it over the next couple of days…
Also, there’s a great article detailing the installation of it in a virtual machine at http://www.techcrunch.com/2009/11/19/guide-install-google-chrome-os/

It’s just Google Chrome with a battery indicator, WiFi indicator, and a couple extra buttons.
Nothing special.
Oh, and when I installed it in a VM on my iMac, it was slow, painful, buggy and horrible.
If you want to try it out – http://google.com/chrome there you go.