There are a handfull of reasons why social media has taken off in the recent past.
Technology, no doubt has provided the platform. But, Sites like Twitter, Facebook , Friendfeed, Delicious all just took off in the last 2 years.
One key reason why social networking has become so popular especially over the last 2 years – is the availability of experienced and qualified professionals – out of jobs with plenty of time to kill. They had in their hands an easy tool to display their knowledge and even monetize it- all for no upfront cost.
The west is crying over jobs being lost in manufacturing and other sectors, while Right under our nose a new market possibly an entirely new sector of economy has taken deeper root.