Is The Social Media Revolution a Fad?

I just came back from a very interesting meeting of Suffolk County Librarians where the topic was "Social Media" (Facebook, Blogs, Twitter, MySpace, etc.)  Most of the librarians in the room seemed to participate in one or more of these social media sites, whether it was a personal account or an account on behalf of the library they work for.

One librarian shared with us a very interesting video clip she found on YouTube.  It's full of facts and statistics on how people all over the world use these social media sites and how quickly it's gaining popularity... but don't worry, like most presentations today it has cool graphics and great music behind it, so it's not boring!  I'd be curious on everyone's thoughts after watching this.  How many social media sites do you participate in?