Not Clearly Pro or Con to the question "Are Social Networking Sites Good for Our Society?"
"People are spending ever more time on social networks, and some are getting into trouble over it. For context, Nielson Online reports that the 70 million Facebook members in the US spent 233 million hours on the site in April 2009, up from 28 million hours by 23 million members the previous April -- a 175 percent increase in per capita usage. And according to a study by Nucleus Research in Boston, the most avid users are spending two hours a day on the site while they are at work -- helping to cost companies whose employees can access Facebook 1.5 percent of total office productivity...
Most people will not imperil their psyches if they spend a little more time on social-networking sites. For them, two hours a day on Facebook may simply mean two hours less in front of the TV. But for people who bring a compulsive personality to the keyboard, those hours can grow rapidly, setting off a cascade of bad consequences at home and work... In the US, the group at risk is pretty big: one in 50 adults has some degree of obsessive-compulsive disorder."
"Are Social Networks Messing with Your Head?," Scientific American Mind, Jan./Feb. 2010