By Ryan Kim, GigaOMAndroid has surged past iOS in ad impressions on Millennial’s ad network for the first time, breaking a two-month tie that suggested a possible lull in the growth of Google’s mobile platform. Android now represents 46 percent of ad impressions in December, compared to 32 percent for iOS after the two OSes were tied at 38 percent in November. Millennial said Android has also widened its lead in ad revenue from applications with 55 percent compared to 39 percent for iOS. While the numbers reflect the obvious continued growth of the Android platform, it also solidifies the idea that Android has become the top platform for mobile advertising, which is fitting considering Google’s strength in advertising. As previous GigaOM commenters have chimed in, maybe we shouldn’t be as surprised because Android apps are designed around presenting ads. This may be instructive for developers trying to monetize their apps through ads. But as we’ve seen through evidence, iOS appears to have more revenue opportunities through paid downloads and in-app purchases. For Google, the latest Millennial numbers are another sign that Android is still growing and matches other sales data that suggest the platform is seeing no let up in momentum. But with the introduction of a Verizon iPhone, it will be interesting to see if the numbers continue in this direction or if Apple grabs back some of its share of impressions. Millennial is the largest independent mobile advertising network. Millennial said Android requests have grown 3,130 percent since January and 141 percent from the third quarter to the fourth quarter 2010. Apple iOS requests have grown by 12 percent from the third quarter to the fourth quarter, and 14 percent since the beginning of the year. Requests on the iPad, however, grew 280 percent in the fourth quarter sequentially, which suggests tablets are going to be a key player in mobile advertising.