The OS, which is named as the Chrome OS, is actually only a Linux distribution built using the developer version of the Google Chrome web-browser for Linux at it's core and is not by Google.
The Chrome OS by SuSE, which comes pre-installed with the Chrome web browser should not be confused with the Google Chrome OS which will be available for download in 2010 after an official announcement by Google. Below is a screenshot of the Chrome OS by SUSE.
Like any other Linux distribution, the Chrome OS by SUSE can be downloaded for free. Unfortunately! a Live-CD version is not available.
To try it out, head on to this page and follow the instructions. Please note that it's not the official Google Chrome OS which was promised by Google in June this year.