Android is Linux based.
As tincholio says, I added the word true on purpose. When you use a real linux stack, things like this are possible:
http://wiki.maemo.org/Easy_Debian
http://temporaryland.wordpress.com/2010/01/20/openoffice-org...
The N9 shows they had a viable, potentially world beating platform. Not only have they thrown it under a bus but, with its passing, so goes any hope of a true linux based smartphone (and accompanying ecosystem) ever achieving mass market exposure. It's tragic.