The planned IPO is notable because it’s the first time that a pure-play mobile ad company has gone public. Most of Millennial’s other competitors have been acquired instead, most notably by Apple and Google, the company’s primary competitors.

The company’s S-1 reveals that the start-up lost $7.1 million on sales of $47.8 million in 2010, and $417,000 on sales of $69.1 million in the first nine months of last year. Millennial’s business is focused on selling advertising that runs on mobile apps, and it says it reaches 200 million users worldwide; in December it processed 40 billion ad impression.

The Baltimore-based company says it most recently gave itself an enterprise value of $305 million. That was back in September 2011, when it granted a block of options. The company’s primary backers are New Enterprise Associates, Charles River Ventures, Columbia Capital and Bessemer Venture Partners.

The funding comes from Bessemer Venture Partners, Columbia Capital, Charles River Ventures and New Enterprise Associates (NEA).

To date, the Baltimore-based company has raised $65 million. But that hardly seems sufficient when fighting Goliaths like Apple and Google, which both made multimillion-dollar acquisitions last year in the space.

Previously, CEO Paul Palmieri said it was Millennial’s intention to stay an independent company, and therefore aim for an IPO. Is $65 million enough?

The funds will be used for acquisitions in 2011, and to invest in the company’s international business, which is considered smaller than its competitors’, such as Google’s. So far, it has built a team in London, and has begun to expand to the Asia-Pacific region.

Market share statistics are notoriously poor in the space, but in December, IDC estimated that Millennial was the largest independent mobile ad network at 15.4 percent, trailing behind Apple with 18.8 percent share and Google/AdMob with 19 percent share. Millennial’s share was estimated to be larger than Yahoo’s 10.1 percent share.

Millennial declined to give specific numbers, but said it achieved “operational profitability” in 2010, and tripled its revenues during the year.

Although it has also been rumored to be an acquisition target, after the recent sales of AdMob to Google (GOOG) and Quattro Wireless to Apple (AAPL), mobile advertising firm Millennial Media is doing some buying of its own.

That would be its just announced acquisition of TapMetrics, a San Francisco-based mobile analytics firm.

Baltimore-based Millennial is one of the larger mobile ad networks in the U.S., but will surely need more scale in the current period of consolidation if it is to stay independent.

Millennial has raised just over $37 million in venture funding, including a $16 million round in November, from firms such as Bessemer Venture Partners, Columbia Capital, Charles River Ventures and New Enterprise Associates.

Terms of the transaction to buy TapMetrics–which has only raised a seed round–were not disclosed.

Here’s the official press release:

MILLENNIAL MEDIA ACQUIRES TAPMETRICS
Adds Deep Cross-Platform Mobile Analytics Capabilities to Existing Developer Program

SAN FRANCISCO, CA, and BALTIMORE, MD, February 23, 2009–Millennial Media, the largest independent mobile advertising network, announced today that it will acquire TapMetrics, a San Francisco-based mobile analytics firm, focused on application usage and behavior.

TapMetrics software suite provides detailed analytics to enable developers to better manage their application sales and revenue in a sleek, intuitive dashboard. By adding TapMetrics, Millennial Media will offer developers more capabilities across mobile platforms:

• Real-Time, Highly Detailed Analytics
• User Interaction Information
• Feature and Version Adoption
• Device Types
• Crash Reporting
• Competitive Ratings System
• Buzz Tracker & Reviews

“The market has recognized Millennial Media as the leader in mobile advertising. As a result of their deep commitment to advertisers, they deliver the best business partnership and monetization for mobile companies–particularly developers,” said Chris Brown, Co-Founder and CEO, TapMetrics. “What is exciting to us is that Millennial Media now has the only scalable solution for developers that doesn’t contain an operating system bias, making Millennial Media the natural partner for us.”

“When we raised our growth round of financing in November, we stated that we would make investments to accelerate our growth,” said Michael Avon, Executive Vice President and Chief Financial Officer, Millennial Media. “We are acquiring TapMetrics, because the company shares our approach to serve the needs of developers, regardless of mobile platform. In addition, TapMetrics’ data and analytics capabilities complement our company’s own focus and development plans. We continue to actively evaluate other potential acquisitions to further expand our business.”

Millennial Media operates the leading mobile advertising platform worldwide. Since adding $16M to its strong cash position in November, Millennial Media has expanded its offerings to key customer segments, to include OEM and platform partnerships that seek to access its strong base of developers and publishers. Additionally, Millennial Media’s employee base has grown by more than 20%, as it continues to expand operations in the U.S. and Europe.

On February 16, 2010, the company released other key 2009 year over year mobile advertising growth figures, including:

• Brand business grew 756%; Performance business grew 171%
• Average deal size increased 353%
• Non-U.S. impressions increased 175% year over year
• 357% increase in Apple OS impressions
• 90% increase in RIM OS impressions
• 81% reach of the Mobile Web users

For more information on growth statistics, please visit www.millennialmedia.com/research and download the full 2009 Year in Review.

Millennial Media is headquartered in Baltimore, Maryland; and has offices in New York, Los Angeles, San Francisco, Chicago, Atlanta, and London. TapMetrics will continue to be based out of its San Francisco headquarters. Terms of the transaction were not disclosed.

Today, in yet another episode of the Web 2.0 lottery, Social Gaming Network grabbed $15 million in funding for its widgety gaming apps that are popular on Facebook and other social-networking sites.

The round, led by Greylock Partners, Founders Fund, Columbia Capital and Novak Biddle Venture Partners, will go toward expanding its offerings, which include the popular Warbook, and also its network for other developers to create and publish online games on.

SGN grew out of Webs.com, which used to be known as Freewebs.

While BoomTown often makes fun of viral apps, most of which are faddish and juvenile, the better made gaming apps actually are likely to be a real business over time, as long they remain engaging and fun to play as the classic real-life games are.

After all, who ever gets sick of Candyland?

SGN’s games are not quite that, focusing more on strategy and bang-bang that 12-year-old boys of any age so love, but, CEO Shervin Pishevar promises, with increasingly rich features and better graphics.

The business plan? Advertising, of course, especially sponsorships, as well as the sale of virtual goods and premium offerings.

SGN’s other popular online games include FightClub, StreetRace, Jetman, Text Twirl and Free Gifts. It has 1.1 million daily active users mostly across Facebook, but also on Bebo, hi5, and MySpace.

In the space, its main competitor is Zynga (here is a post and video with its founder, Mark Pincus). Naturally, the two bicker back and forth in the blogosphere about size and quality of games.

But it seems to me that there is room for both, so the fighting seems like a lot of noisy, well, game-playing.

Here’s Pishevar talking about the sector: