Social marketing, once viewed solely in terms of gaining “earned” media attention—awareness, engagement, feedback—is scaling into a true marketing channel. The cause: the blurring between earned and paid media. Participatory social interaction is now leveraging both into a unified, single recommendation engine.

“Recommendations have long been considered the most trusted form of "advertising,' according to Nielsen Co.'s "Trust in Advertising' surveys,” said Ben Grossman, communications strategist at agency Oxford Communications, Lambertville, N.J. “The great challenge for advertisers has been that recommendations don't have the reach, frequency and number of impressions as real paid ads.

“With social media, advertisers now have the opportunity to amplify recommendations at scale,” he said.

A good example of the phenomenon is Facebook's Sponsored Stories feature, rolled out in January, which turns the actions of friends into business or product recommendations. Marketers, armed with knowledge of members' activities through the Facebook News Feed—such as “likes,” check-ins, page posts and custom applications like discount offers—can feature those actions in the column on the right to those members' friends.

When viewers see these ads—capable of being delivered with the same scale, frequency and reach as traditional ads—they may consider their friends' actions as company or product recommendations.

A more traditional but similar social ad unit is Twitter's Promoted Tweets, introduced last year. Here, advertisers pay for tweets that appear at the top of search pages on Twitter.com. The tweets, based on keywords on which advertisers bid, can be retweeted by Twitter users to their own followers, just like ordinary Twitter posts, a process that once again can have the impact of recommendations.

“We were initially concerned that these promoted tweets wouldn't perform because we weren't sure they'd feel authentic,” said Noah Mallin, VP and group director-social marketing at global integrated brand agency Digitas, New York. “But they've been working well for us; we've gotten a response that's noticeable. We believe this can work if the message is right, [if] it leads people to participate and is not just a one-way community.”

The “social at scale” trend is based on people getting excited about content, whether that content is delivered as a post or an ad. When they share that excitement, people can go to market for a brand.

“One thing we always encourage is transparency to build trust,” said Lisa Arthur, CMO at marketing software and services company Aprimo Inc., noting the need for paid social ads to do the same. “We are in an environment today where customers are very cynical about marketing messages. The recent economic climate has made [them] even more cynical.

“Transparency in building a trusted relationship must be at the heart of all social marketing,” she said.

Arthur has not seen as rich a return from social ads as from free content, tweets and LinkedIn posts, content that leverages the network effect of a trusted environment.

But hybrids that combine earned and paid social media, such as Facebook's Shared Stories, continue to be introduced. For example, advertisers are beginning to employ rich media ad units, which can include just about anything, including live social feeds.

“These rich media ads can go on your own website or on an ad network,” Oxford Communications' Grossman said. “I'm starting to see major brands integrating their social feeds, which are trusted recommendations, into these ad units.”

A prime example, he said, is the new website of an Oxford client, consumer and auto electronics company AudioVox Corp. The site, unveiled this month, features a “social panel” along the bottom featuring live social interactions the company is having with its customers. The idea is to demonstrate to the investment community that the company has lively customer relationships.

The panel is, essentially, an onsite banner ad, but Grossman said there are some safeguards built in to the AudioVox site to protect against broadcasting negative comments.

“It's no secret that this isn't for companies that are faint of heart,” he said.

A similar melding of earned and paid social media was a recent Oxford campaign on behalf of Brother International, promoting its new large-scale printer-scanner. The campaign, “See the Bigger Picture,” featured LinkedIn display ads that drove viewers to a landing page where small-business owners could describe how a printer that produces 11-by-17-inch documents might help them in their businesses.

Home-crafted videos were a favorite medium among responders, who were entered into a contest where weekly prizes, as well as a grand prize of $10,000, were awarded.

Whether the earned-plus-paid combination can produce results greater than the sum of its parts is as yet undetermined. But if social participation already is huge, social advertising is getting there as well.

According to a report released last month by online intelligence company comScore, U.S. Internet users were exposed to about 1.11 trillion display ad impressions in the first quarter of this year. Facebook accounted for more than 346 billion of them—a 31.2% share.

That almost doubled Facebook's share recorded in the same period a year ago and was up from the 25.8% share of all digital ads served in the fourth quarter of 2010. Facebook is extending its display-ad lead over Yahoo sites, which in the first quarter delivered 112.5 billion impressions, or 10.1% of the total, a bit higher than its 9.7% share the previous quarter.