The Times says Conservative Blogs are More Effective:
Liberals use the Web to air ideas and vent grievances with one another, often ripping into Democratic leaders. (Hillary Clinton, for instance, is routinely vilified on liberal Web sites for supporting the Iraq war.) Conservatives, by contrast, skillfully use the Web to provide maximum benefit for their issues and candidates. They are generally less interested in examining every side of every issue and more focused on eliciting strong emotional responses from their supporters.
What we do over here (in general) is discuss issues. What conservatives do (in general) is propaganda. Exceptions exist on each side, but the trend is persistent.
More conservative blogs edit, moderate or simply ban comments. Liberal blogs tend to have open comment threads without any moderation, or with just enough to prevent libel, spam and other abusive practices.
One can define success or effectiveness as getting your agenda into other parts of the spin machine, or you can define it as engaging average citizens in national debates. Conservatives aren’t so effective at the latter, liberals are still developing the spin machine for bloggers to plug into.