The last major independent mobile ad network Millennial Media (which was considered to be acquired by RIM at some point) has raised $27.5 million in funding. This latest funding round, which involved Bessemer Venture Partners, Columbia Capital, Charles River Ventures and New Enterprise Associates raises Millennial’s total funding to $65 million.

“Millennial tripled revenue in 2010 from 2009 and achieved profitability. According to IDC research published last December, Millennial Media was on target to make $35 million in U.S. mobile advertising revenue for 2009, so revenues could be well over $100 million.”

According to IDC, Millennial’s ads reach 81 percent of the U.S. mobile web. While it managed to keep a relatively low profile considering its size, Millennial Media is involved with the entire mobile ad industry. SiliconANGLE extensively covered Millennial’s reports, including a recent one which discussed Apple’s dominance over the mobile hardware industry and a report discussing Google’s – and Apple’s – share of the market, as well as their growth trends.

“The mobile model continues to expand beyond the phone, and is becoming the new, device based internet via apps on everything from refrigerators to tablets to televisions,” said Paul Palmieri, president and CEO, Millennial Media.  “Our market position, proposition to the mobile and app economies, and ability to show exceptional results is already solidifying our central role in the digital advertising business.”

While Millennial may be a major holdout, it’s certainly not the only one. There’s also the San Francisco-based Greystripe, whose mobile advertising website launch we covered here, and AdMob, who recently lost an exec to Mojiva and whose acquisition by Google we covered here.