Via Kevin Drum, an interesting study using network analysis of political blogs - who links to what, and what they talk about.

One of the most interesting findings is that the liberal bloggers are more likely to talk about Donald Rumsfeld, and the conservatives are more likely to talk about Michael Moore. In other words, a big part of the discourse in one's political tribe involves complaining about the other tribe.

This seems to me to be a less than healthy mode of discourse. Listen to Al Franken or Rush Limbaugh and you'll see what I mean.