Perhaps I blogged about this study before, but it deserves mention again as we see new orgs move more and more to integrating Facebook and other social networking sites into their content.
This study (abstract here, pdf here) is based on a survey of 3,500 young adults (ages 18 to 24) and finds little or no influence by social networking sites on political knowledge (see especially Table 4). Now this controls for a bunch of other media exposure items, so I'm not terribly surprised there was little variance left for social networking to explain. Still, it tells us a little something about what social networking does not do.
I also found the factor analysis interesting. For the uninitiated, a factor analysis lumps together similar responses to a variety of survey questions. Here, the two social media items fall together nicely and are distinctly separate from other media (see Table 2), from late-night comedy shows to traditional news shows, sites, and publications. And, separate from mobile media like smart phones.
Oh yeah, and it's a great study because it cites me.