A new paper by Aaron Shaw and Yochai Benkler looks the differences between left- and right-wing political blogs during the summer of 2008. From the abstract:
An examination of the top 155 political blogs reveals significant cross-ideological variations along several dimensions. Notably, the authors find evidence of an association between ideological affiliation and the technologies, institutions, and practices of participation. Blogs on the left adopt different, and more participatory, technical platforms, comprise significantly fewer sole-authored sites, include user blogs, maintain more fluid boundaries between secondary and primary content, include longer narrative and discussion posts, and (among the top half of the blogs in the sample) more often use blogs as platforms for mobilization.