Erik Qualman of Socialnomics has put together a great video called "Social Media Revolution". Worth watching and then checking his datapoints and footnotes (a couple of which I included below): A couple interesting footnotes from Socialnomics:

#1. By 2010 Gen Y will outnumber Baby Boomers….96% of them have joined a social network #10. % of companies using LinkedIn as a primary tool to find employees….80% #13. 80% of Twitter usage is on mobile devices…people update anywhere, anytime…imagine what that means for bad customer experiences? #31. 25% of Americans in the past month said they watched a short video…on their phone #32. According to Jeff Bezos 35% of book sales on Amazon are for the Kindle when available