Thanks to Ian M. for pointing out this great report (pdf) on mobile app development. In gives a very comprehensive view of the development ecosystem.
Mobile Developer Economics 2010 and Beyond
Here is a small except taken from the author’s synopsis in his blog. The charts in the original article are particularly interesting.
Indeed Android stands out as the top platform according to developer experience, with close to 60 percent of developers having recently developed on Android […] iOS (iPhone) follows closely as the next most popular platform, outranking both Symbian and Java ME, which until 2008 were in pole position.