I haven't yet read Eric Alterman's book What Liberal Media, but Jonah Goldberg's review raises a noteworthy point:

Sure, conservatives have built a parallel media structure. No secret there, even if Mr. Alterman makes it sound like it is one. (If we've spent billions, though, I feel cheated. Most of what I see operates on a shoestring.)
But back up a step: Why did conservatives feel a need to set up parallel media channels, with all the effort that entailed? Because the existing structures--elite newsrooms, plus the academic, publishing and entertainment industries that intertwine with the news business--are so hostile to conservative views that the only way to compete in the public debate was to set up shop across the street.
...But anyway, why is it dangerous to democracy if conservatives who view the media as too far left try to pull them back? That sounds like healthy democratic activism in action. Besides, Mr. Alterman's doing the same thing, trying to move the media left. So what is the big deal?

For another day: what this has to do with the blogosphere. (A lot, I think.)