This is sort of interesting, over here at Crooked Timber
and they've got a very pretty graphic here:
What they're concluding is what you might guess
Of course, it is possible that all interlinking across liberal and conservative blogs happens in a manner that is void of substance. To address this point, we undertook a content analysis of a subsample of the posts in our study (140 for now to be exact). We found that about half of the links represent what we classify as strawman arguments. The liberal bloggers in our sample are more likely to engage in such cross-linking than the conservative bloggers. However, we also found some evidence of substantive cross-linking. In these cases bloggers may either agree or disagree with the other person, but they do address the content of the other blogger’s post. Also, we did not find that bloggers address the substance of those who resemble their point-of-view very often either. (We present specific figures on the conference poster.)
Overall, it would be incorrect to conclude that liberal bloggers are ignoring conservative bloggers or vice versa. Certainly, liberal bloggers are more likely to address liberal bloggers and conservative bloggers are more likely to link to conservative bloggers. But people from both groups are certainly reading across the ideological divide to some extent.
What you guess and what you can support are, however, as I point out to my ENGL 1213 students, two different things. So it's a post worth looking at all the same. And some good points in the comments.
Can I just add -- blogs are so cool.
6 hours ago