Olds is right. Nielsen reported that users 55 and older are the fastest growing group on social networks. However, people aged between 18 and 34 are the most active age group.

"I think social networking might have reached that 'killer app' status where it draws people into computing who haven't been there before," Olds added.

The report, which just came out this week, also notes that people are increasingly using sites like Facebook and Twitter when they're shopping.

According to Nielsen, 70% of active online adult social networkers shop online, 12% more likely than the average adult Internet user.