Is Android based upon Linux? Is Android based upon Linux?
Yes, here is the source code download and what you need to use it.

http://source.android.com/download


And the license agreement: http://source.android.com/license
Home Page: http://www.android.com/
The wiki: http://en.wikipedia.org/wiki/Android%5F%28operating%5Fsystem%29


From the wiki:


  At Google, the team led by Rubin developed a mobile device platform powered by the Linux kernel which they marketed to handset makers and carriers on the premise of providing a flexible, upgradeable system.