In terms of volume that is, not in terms of revenue. Apple still leads the latter on both phone sales and after market sales.
Android grabs 53% of global smartphone market share; iOS 50% of application revenues
“The report states that games, mobile social networking, and music/entertainment applications are the top application categories.”
Note though that social networking apps are almost always free, and without ads, so the real money is in games and music/entertainment.
I’m wondering though, when will e.g. the Facebook app have ads? That would increase revenue considerably.