Don't turn around Apple, Android may be gaining on you. Google's mobile operating system accounted for more than a quarter (27%) of U.S. ad requests on smartphones in the fourth quarter, according to the latest metrics from AdMob. Android's share of U.S. mobile ad requests is now clearly second only to the iPhone OS, which still dominates the market with a 54% share.
Android roughly doubled its U.S. share each quarter in 2009, starting at 4%, while Apple's has hovered just over 50% except for a surge up to 65% in the second quarter. (Worldwide, Android had a 16% share and the iPhone, 51%.)
Android's U.S. gains have come at the expense of both BlackBerry-maker Research In Motion and Windows Mobile. RIM's share of ad requests dropped from 20% to 10% during 2009 while that of Windows Mobile fell from 12% to 3%.
The smartphone ad market is shaping up as a two-platform contest between the iPhone and Android. That battle will only heat up further this year, following Google's planned acquisition of AdMob and its launch of the Nexus One, with more Android phones on the way. Likewise, Apple has signaled its ambitions for expanding in mobile advertising with its bid for Quattro Wireless.
Smartphones will play a big role in mobile advertising either way. High-end devices made up only 14% of phones shipped in 2009, but generated 39% of worldwide traffic on AdMob's network.