SitDown. StartUp.

Mobile ad networks got a big piece of validation last week when Google paid $750 million for AdMob, one of the leaders. But they also got a new problem: Google, one of their most logical acquirers, is probably on the bench for a while now.

Still, with plenty of hope for huge growth, we expect to see a lot more news like this: Baltimore-based Millennial Media, another leading mobile ad network, has just raised $16 million in Series C financing, led by New Enterprise Associates. Previous investors Bessemer Venture Partners, Columbia Capital, and Charles River Ventures also participated.