Google's Android operating system dominated mobile ad impression share through January, collecting 54 percent of hits compared with 28 percent of hits for Apple's iOS on Millennial Media's network.
Research In Motion took third with 14 percent of impressions, down from 16 percent through December. Android's January ad impression numbers are up 10 percent from December, when it registered 46 percent to break a two-month statistical tie with Apple's iOS.
Millennial Media had Android and iOS tied for 38 percent of ad impression share in November, with each platform commanding a 37 percent share through October. While Android storms up the ad charts, iOS ad impression share dropped 4 percent from its December total of 32 percent.
This is not to say that iOS has turned into a lame duck on Millennial, which found that iOS outpaced all other operating systems in ad requests with a 47 percent increase from December to January. That compares to Android's 32 percent boost.
Moreover, Apple is the leading device manufacturer on Millennial's network, with its iPhone, iPod Touch and iPad comprising 26 percent of the top 15 manufacturers impression share in January. That's a 24 percent increase month-over-month.
The latest numbers underscore just how much Apple iPhone and Android smartphone adoption has grown in the last several months. Apple sold 16.24 million iPhones and 7.33 million iPads through the quarter ending Dec. 31.
Meanwhile, Android sees 300,000 activations a day, shipments of more than 10 million Samsung Galaxy S units, and its high profile on Verizon Wireless' Motorola Droid line. Indeed, Android handsets helped HTC nab the No. 2 position in Millennial's top 15 manufacturers list, with 21 percent.
Canalys, Nielsen, comScore, IDC and Gartner all have charted Android's smartphone share rise through 2010 and into 2011.
More importantly for this discussion, Piper Jaffray analyst Gene Munster estimated Google could have an average of 133 million Android users by 2012, each generating $9.85 per year on advertising, meaning Android would kick in $1.3 billion to the company's ad revenues.
This highlights the difference between Google's and Apple's approaches to mobile. Google makes bank on mobile ads, while Apple wants to sell hardware with some software revenues.
What Millennial and others will watch closely is any shift in iOS' impression share starting Feb. 10, which is when Verizon Wireless began selling the iPhone 4.