Great overview of recent analysis of social media by the Pew Research Center’s Project for Excellence in Journalism.
Among the highlighted findings:
"Social media and the mainstream press clearly embrace different agendas. Blogs shared the same lead story with traditional media in just 13 of the 49 weeks studied. Twitter was even less likely to share the traditional media agenda — the lead story matched that of the mainstream press in just four weeks of the 29 weeks studied. On YouTube, the top stories overlapped with traditional media eight out of 49 weeks."