The Pew Research Center released it’s “The State of the News Media 2012” today, and it includes commentary on social media. Pew says that social media “are important but not overwhelming drivers of news, at least not yet.” The go on to say that “the notion that large percentages of Americans now get their news mainly from recommendations from friends does not hold up” and that “No more than 10% of digital news consumers follow news recommendations from Facebook or Twitter ‘very often'”.
The full discussion of social media goes on go differentiate between how people get news on Facebook, which is mostly from family and friends, and Twitter, where people get news from a larger circle of people. This is not surprising, though, when you consider that you generally only see people you “friend” on Facebook but you can see all of Twitter (more or less).
The full report is well worth reading; you can find it here.