Google Chrome OS is an open source, lightweight operating system that will initially be targeted at netbooks. Later this year we will open-source its code, and netbooks running Google Chrome OS will be available for consumers in the second half of 2010.
http://googleblog.blogspot.com/2009/07/introducing-google-chrome-os.html

____

"So today, we're announcing a new project that's a natural extension of Google Chrome — the Google Chrome Operating System."