Millennial Media, the largest independent (and soon to be public) mobile ad network operator, announced the latest addition to its portfolio. The App Engagement Program is designed to provide marketers a way not to reach new customers, but rather to build on viewers’ initial interest and extend it to additional transactions over-time.

The Engagement Program offers an entirely new layer of targeting. Millennial can identify users who already downloaded a given app and use that data to redirect them back into the app or other relevant content, instead of displaying the same marketing material. The level of engagement is analyzed and campaign managers can view consumer interaction with their apps, similarly to how Google Analytics enables site owners to identify the most popular sections.

“Consumers now expect brand name companies to have a mobile app, yet it still takes a concerted effort from the brands to drive adoption,” said Jamie Fellows, SVP of Product at Millennial Media. “Brands need to make sure the experience is good, they need to make sure users are finding the app, and perhaps most importantly, they need to take steps to drive sustained consumer usage.”

This is the second product launch Millennial had this month. Previously it launched a new developer tool that enables them to embed ads within their apps using a web-based interface.

The ad network operator is strengthening its portfolio on fairly regular basis, an approach that has paid off when considering Millennial Media’s current position in the market. All the growth the company has seen spurred a whole lineup of rumors concerning a potential merger or IPO, and Millennial itself provided the answer for that in early Jan. It has filed for a public offering with the SEC, though did not disclose a date or the sum it hopes to raise as of yet.