Privacy concerns intensify when Web sites get social because people want control over what information they share, and with whom. Or at least they say they do, according to surveys by the Pew Internet & American Life Project.

Their actions, however, can be contradictory.

"Our surveys have shown that people send mixed messages about privacy," said Lee Rainie, director of the project. "When asked directly, they place a high value on it. They express a strong desire for control over their personal information and how third parties use it."

But in their day-to-day activities, people are willing to go against their principles and share quite a lot in exchange for something they value. Companies navigating this environment, Rainie said, "are getting a series of messages from consumers that are sometimes hard to figure out."

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