Adamic, L & Glance, N. (2005). The political blogosphere and the 2004 US Election: Divided they blog. Proceedings of the 3rd international workshop on Link discovery, p.36-43.
full text pdf
A lovely example of the echo chamber effect in online conversations. In this paper, Lada and Natalie analyse an impressive amount of linking data to identify how often the top 40 political blogs linked to one another. They found that the two parties kept themselves to themselves, linking between one another very little. Interestingly, the conservatives were more likely to link to the liberals than the other way around.
Great study. Still stands.