Millennial Media, the second largest player in the mobile advertising market after Google’s Admob, has just filed to go public in 2012. It aims to raise $75 million.

Android has overtaken iOS as the most popular mobile advertising platform. It now has a 46% impression share on Millennial’s ad network, compared to 32% for the iPhone.

Angry Birds for Android will soon reach $1 million per month in advertising revenue. It is one of the biggest mobile success stories ever.

Google acquired an ad technology startup invite media on Wednesday this week. Invite media helps buyers purchase advertising from a dashboard displaying multiple ad exchanges in real time.

The Federal Trade Commission has approved Google’s $750 million acquisition of Admob.