Not long after a report was released that Android had overtaken the iPhone in U.S. marketshare comes a report from AdMob stating that iPhone OS devices are outnumbering Android 2:1 in the U.S.  AdMob, officially a part of Google as of today, has released a report measuring the number of unique devices that requested an ad from AdMob at least once during April 2010.  During April, AdMob says that there were 10.7 million unique iPhones accessing AdMob, compared to 8.7 Android devices.  When we include iPod Touches and iPads in the equation, the iDevice number jumps to 18.3 million unique devices.

Worldwide, the story is largely the same.  AdMob says that there were 11.6 million unique Android devices compared to 27.4 million iPhones, and that numbers jumps to 40.8 million when you include all of Apple's iDevices.  When breaking down the OS distribution worldwide, AdMob reports that Android is considerably more popular in North America than the rest of the world, as we have 75 percent of the world's Android devices here, compared to only 49 percent of iPhones.

When considering the actual number of ad requests, the iPhone OS is still the leader worldwide at 42 percent and Android at 25 percent, ahead of Symbian and BlackBerry at 2 percent and 1 percent, respectively.  In the U.S., however, Android is in the lead with 46 percent of ad requests.  The iPhone OS is in second place with 38 percent, followed by BlackBerry at 7 percent and webOS at 3%.

Via AdMob, Boy Genius Report