According to mobile ad firm Smaato, U.S.-based Symbian users are 2.7 times more likely to click on a mobile ad than their iPhone OS using countrymen. The findings, based on 6 billion ads served up by 40 ad companies in the month of April, are quite puzzling when considering the infinitesimally small share of the U.S. smartphone market Symbian currently occupies. But GigaOm’s Kevin Tofel has what sounds like a very reasonable explanation for the stats: “Symbian is a more mature operating system in terms of age, and both advertisers and developers have used that time to optimize mobile advertising on the platform. Apple’s iPhone OS is a relative youngster compared to Symbian, having only initially launched on a product in June of 2007.” Kind of makes one wonder why the FTC is making such a stink over Google’s attempt at acquiring AdMob and the launch of Apple’s iAd. Moving on… Anyone else think it’s pretty incredible that feature phone users click on more ads than Android, BlackBerry, Palm and Windows Phone users?