The social networking world is full of friends you never see. But more than 500 social media enthusiasts will meet -- in person -- this weekend at the PodCamp Pittsburgh conference.

The conference came to Pittsburgh four years ago for the podcasting demographic of the technocracy, but has expanded with the Web to include Twitterers, bloggers and Facebookers, to name three popular ventures.

Companies such as Direct Energy join a roster of more than 85 sponsors who are subsidizing the free event, held at the Art Institute of Pittsburgh, Downtown. Ginny Montanez, the blogger formerly known as PittGirl, is on the schedule alongside sessions with titles such as "Take a Screencast, It'll Last Longer."

How can Pittsburgh sell out an event seemingly catered to savvy centers such as San Francisco or Boston?

The Steel City's smaller population has an unexpected effect on social networking, said PodCamp organizer Cynthia Closkey. She is president of Big Big Design, a Web site design firm in Butler.

"It's a heavily interconnected population here, and that helps when you're online looking for people you know," she said.

A new user signing on to Facebook or Twitter first searches for online acquaintances, she said. Pittsburgh's small-city population increases the concentration of possible acquaintances.

Of course, it helps that a significant portion of that population is the tech-savvy communities at local universities and startups. But organizer Norman Huelsman said PodCamp attracts everyone from social media gurus to the new user unsure what part of speech "Tweet" is.

"It's a free conference for the Joe Schmo who wants to learn more about it," he said. It gives the organizers the chance to evangelize a little, since the more, the merrier when it comes to social networking sites.

Mr. Huelsman is what Ms. Closkey called a "professional amateur": a blogger who has a "real" job, too. Mr. Huelsman is the assistant director of public relations at the Art Institute.

Ms. Closkey thinks a big topic of conversation this year will be networking sites such as Twitter or Facebook, which are increasingly turning into "assumed tools" for organizations.

"Until now, people viewed these sites as the cookie or dessert, and not the real, solid food," she said. That's changing since all kinds of companies are realizing the potential advertising opportunities.

But for all of the marketing opportunities, Ms. Closkey foresees an inevitable backlash toward the sites. Posting a notice on Facebook might be free advertising, but "the parts that aren't free are the time, and the employee or manager who has to monitor the pages," she said.

Although the event is sold out, more information is available at www.podcamppittsburgh.com,

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