By Dan Lindley

Professional network LinkedIn has launched the LinkedIn Audience Network, an ad network with a partner that works with 100 well-known media outlets including Reuters and the Hearst Corp. Though the network will serve display ads, rather than classifieds, it offers an example of LinkedIn’s powerful attraction to advertisers in an online-networking space that so far has been a disappointment, advertisingwise. That’s largely attributable to LinkedIn’s vaunted ability to target high-value markets of career professionals.

We chatted via telephone late last week with Steve Patrizi, LinkedIn’s director of advertising sales, and Krista Canfield, the company’s PR manager, to get some insights into the new venture and into the fast-growing professional network itself.

One bit of fallout from that growth immediately became apparent: The call started a few minutes late as Patrizi and Canfield scrambled to find an unused conference room at LinkedIn’s headquarters deep in the heart of Silicon Valley, in Mountain View, Calif. Free space has become harder to come by as the company’s number of employees, members and business ventures continues to grow. But “that’s a good problem to have,” Canfield noted.

LinkedIn’s membership had hit the 28-million mark the day before, Patrizi said. Growth may be continuing because of rather than in spite of the poor economy in the United States. Call it the fear factor. More professionals may be putting their career and educational profiles on LinkedIn, partly in the hope that their accomplishments will attract job offers, freelance work and similar opportunities from other LinkedIn users.

Although the closely held company doesn’t release financial data (Hoover’s estimated $3 million in sales for 2007) Patrizi noted that LinkedIn makes roughly equal amounts of money from four major revenue streams: paid subscriptions from members who want enhanced services, including better access to other members; job postings; profile searches for recruiters and corporations looking for suitable job candidates; and advertising.

The ad network, launched Sept. 15, is part of that last component. Working with New York-based Collective Media, LinkedIn is offering advertisers access to its members when they browse the 100 or so publishers’ sites served by Collective Media. “The basic concept,” Patrizi said, “is to help advertisers reach as many of our 28 million members as make sense to them. For an advertiser interested in selling to small-business people, for example, they can be hard to find on the Web. We are targeting them as a high-value market.”

Collective Media is one of about 75 major ad networks in the U.S.. LinkedIn chose it because its list of premium publishers includes well-known names like Hearst Corp., The Wall Street Journal, Reuters, Associated Press, Discovery.com and National Geographic. These represent “a clean, well-lighted place,” he said, “high-profile” pubs for advertisers who might worry about their brands’ image and about routing their ads through other networks with “cheap metrics” and sales teams with instructions to “sell anywhere.”

That high road fits with LinkedIn’s rather clean-cut professional-networking image.

It also doesn’t hurt that LinkedIn claims that while its members are a bit older than users of social networks MySpace and Facebook, its members are younger, richer and better educated than users of many leading business Web sites. LinkedIn’s rates reflect its desirable audience. While its rate card shows costs of $30 to $76.50 per thousand impressions, depending on which part of its membership is being targeted, many social networks command far less. Most struggle just to break a buck, according to the blog TechCrunch.com.

The formula for LinkedIn seems to be quality over quantity; credibility over credulity, and a certain stodgy solidity compared to random raunchy rawness of the more popular social-networking sites. Not only are LinkedIn’s members more desirable (financially, at least) than memberships of other online networks, LinkedIn’s web of business connections makes it harder for members to post fake profiles and game the system.

LinkedIn’s members “tend to keep information pretty accurate on their profiles,” Patrizi contended. Wouldn’t it be as easy to lie on a LinkedIn profile as to lie on any old résumé? “I’m sure some do that,” Patrizi conceded. “But people tend to sign up to share who they are. If you lie, you’ll be found out fairly quickly. It’s different from other social networks where middle-aged males might pose online as young females.”

“It tends to be self-correcting,” Canfield added, noting that liars would be quickly found out and could be double-checked through their connections.

Whatever the truthfulness of its members, LinkedIn collects a trove of data from them, and they offer up that information gratis. Their profiles tend to be more detailed and current than the data requested by some publishers. With its deep pool of member information, LinkedIn can slice and dice users into groups that might interest advertisers, and price them accordingly. High on that list, for instance, come sought-after groups like small-business and IT professionals; less-in-demand groups, like journalists, alas, command lower rates. Beyond its so-called InGroups of professions, LinkedIn can also create custom lists for advertisers.

LinkedIn’s cookies identify users when they visit LinkedIn and follow them when they wander to other sites within the ad network. Appropriate ads are served to target groups if space is available. Patrizi pointed out that the cookies carry “profile data but no personally identifiable data.” Internet privacy is a potential sore spot that seems likely to grow sorer in coming years. LinkedIn’s users can opt out of the program, like users in many other networks.

For advertisers, the deal means that “they have direct relationships with these publishers” via Collective Media. “We can add targetability,” Patrizi said of LinkedIn’s role in the transaction.  “LinkedIn is about professional appearance,” Patrizi said. “Advertisers could want to target personal appearance.” Recruitment branding could be another category to explore, he said, tying into the social network’s other recruitment services.