Playing with the AdMob data on iPhone and Android devices—which is a bit old now, the U.S., a much bigger iPhone/Android market than the rest of the world, reflects the worldwide distribution of iPhone vs Android devices (the blue is iPhone):
The pattern seems to be mirrored elsewhere, but not evenly. In Australia, particularly, there seems little room for Android right now. Look at China, though: Almost as many Android devices as there are iPhones:
Ironic, really, that Google is so dependent on China to make headway with its phone OS. The third tier of countries follow a similar distribution:
