It doesn't necessarily need to lead, like dkos, it can fact-check the MSM. During the election, I noticed that after awhile, whatever nutty claim came out of republican mouths here, they were quickly debunked by the blogs, and pundits stopped giving the nutjobs credence. This took a few months of aggressive work by bloggers.

Fact-checking is a very, very useful tool to have in your kit, and I think the MSM cares enough about its own credibility to pay heed.

"It Can't Be Just About Us"
--Frank Schnittger, ETian Extraordinaire