Linux Top 5: Ubuntu for Your Smartphone

“During Shuttleworth’s keynote he casually dropped the fact that
he figures Ubuntu has some 20 million users. That’s a non-trivial
amount of users and citizens of the Linux Planet.

That said, Ubuntu isn’t necessarily the most widely used or
deployed Linux distribution. The Fedora Project, which bases its
usage assessment based on the identification of unique IP addresses
that update Fedora packages, shows a higher number of users.