Like a lot of people who use social media, Israel Hyman and his wife, Noell, went on Twitter to share real-time details of a recent trip. Their posts said they were "preparing to head out of town," that they had "another 10 hours of driving ahead," and that they "made it to Kansas City."

While they were on the road, their home in Mesa, Ariz., was burglarized. Hyman has an online video business called IzzyVideo.com, with 2,000 followers on Twitter. He thinks his Twitter updates tipped the burglars off.

"My wife thinks it could be a random thing, but I just have my suspicions," he said. "They didn't take any of our normal consumer electronics." They took his video editing equipment.

Most people wouldn't leave a recording on a home answering machine telling callers they're on vacation for a week, and most people wouldn't let mail or newspapers pile up while they were away. But users of social media think nothing of posting real-time vacation photos on Facebook, or sending out automatic e-mail messages that say, "I'm out of the country for a week."

"I'm amazed at how many people get on there and say they're going on vacation," said Lee Struble, head of security at Monroe Community College in Rochester, N.Y.

Struble, 53, is a member of Facebook with more than 200 friends, many of them classmates from high school and college who recently reconnected through the site. "Some of these people you haven't seen in 20 or 30 years," said Struble. "But they know where you live or can find out pretty easily, they can do a Google Maps search and can get directions to your house, and you're telling them that you're going to be gone."

Struble is careful about his outgoing e-mail messages. "I just tell people I'm going to be out of the office," he said. "I don't say I'm going to be out of town."

New communication technology has always brought with it new risks and rules, usually learned the hard way. Facebook and Twitter are so relatively new that users may not consider all the risks. For Hyman, Twitter was a way to connect with fans of IzzyVideo.com, where he offers how-to videos on video production. His wife teaches scrapbooking through videos at Paperclipping.com. About half of the new episodes they release are free, but viewers pay to access their archives.

"The customers have never met me in person," Hyman said. "Twitter is a way for them to get to know me. You do business with people you know. I'm a real person. I take my kids to the park. I go on vacation. I'm not just some company!"

He added: "I forgot that there's an inherent danger in putting yourself out there."

Despite the potential risks, some social-media fans say they have no qualms about sharing their whereabouts.

"I don't worry about it," said David McCauley of Boise, a social-media consultant who posts a running update of his activities for his Facebook friends. McCauley also communicates constantly on Twitter, where anyone can sign up to read your posts.

"If somebody really wanted to rob me, they could rob me whether they're Tweeting about it or not," McCauley said. "Most people who want to follow you [on Twitter] are typically not thieves, or they're not looking to take your stuff; they just want to follow you and understand you."