Back in 2005 James Surowiecki made an interesting presentation at TED on the Turning Point of Social Media. Looking back, this was one of the first presentations by James Surowiecki on the evolution & growth of Social Media.
Here is a link to James Surowiecki‘s presentation (in case the embedded video does not load). You can check on TED from time to time to listen to these inspiring & innovative presentations from the best speakers in the world.
In another fascinating post on Wired, they published a chart on the time average people seem to spend on social networking sites now a days.
This is a symbolic representation & even if this chart is near reality, people spend an average of about 60% of their time on social networks. In another study across various segments of the US population, it was shown that people on average use at least 4 social networking sites. The popular amongst them are FaceBook & Twitter.