Lauren Barack -- School Library Journal, 2/22/2010

So says a new study from Pingdom, a Swedish-based Web-monitoring firm, which examined Google’s Ad Planner data from 19 of the nation’s most popular social networking sites, including Facebook, Twitter, Friendster, and even Ning. Their findings? It might be Dad who can’t refrain from updating his friends, rather than Junior.
Adults between the ages of 35 and 44 made up 25 percent of all users of these sites—nearly double the 15 percent of all children up to 17 years old who chat away online. But don’t assume that number increases as teens hit college, as only nine percent of adults between the ages of 18 and 24 spend any time on social networking sites. And the age group that connects with friends online the least? Those 65 years old and up, just three percent of the user base. At least for now.
"Although we can’t say how this will change over time, at the moment the older generations are for one reason or another (tech savvy, interest, etc.) not using social networking sites to a large extent," say the authors of the study. "It is also noteworthy that social media isn’t dominated by the youngest, often most tech-savvy generations, but rather by what has to be referred to as middle-aged people (although at the youngest end of the spectrum.)"
However, that’s not to say that Mom and Dad are frequenting the same sites as their children—or that a high school junior is likely to bump up against their school librarian on Ning. In fact, 64 percent of Twitter users and 61 percent of Facebook users clock in at 35 years old and up.
So where do teens crop up the most? On Bebo, a relative newcomer to the social networking group, founded in 2005, with 44 percent of its users aged 17 and younger.
Yet, with Pingdom’s study putting Bebo’s average user at 28 years old, it’s likely the days of Bebo being a teen favorite are quickly coming to an end. Where they will congregate online next, Pingdom can’t predict.