There have been rumors that Google would distribute their own version of Ubuntu Linux, but those rumors have been denied by Mark Shuttleworth, founder of the Ubuntu project.
However, Google has actually developed two variations of Linux: Android and Chrome OS.
Android is a phone and tablet operating system that has very little to do with Linux on the surface, but it actually uses the Linux kernal.
Chrome OS is an operating system for netbooks that also uses the Linux kernal. It does not resemble Ubuntu Linux. Unlike traditional operating systems, Chrome OS is basically a Web browser with a case and keyboard. Chrome is built around the idea of a thin client that uses cloud-based Web apps, while Ubuntu is a full operating system that runs both downloaded programs and Web browsers.