A very interesting research paper by Lada Adamic and Natalie Glance examines the posts of 40 "A-list" conservative and liberal blogs in the two months leading up to the 2004 presidential election. Political Wire is included in the analysis.
Among the findings:
There are significant differences in the behavior of liberal and conservative blogs, with conservative blogs linking to each other more
frequently and in a denser pattern.
Conservative blogs tended to rank higher overall than liberal blogs, with the top 20 conservative blogs falling in the 44 most-cited blogs while the top 20 liberal blogs fell in the top 77 most-cited blogs.
Liberal and conservative bloggers also had clear preferences for mainstream news sources that they cited.