Actually, I never heard of this back in 2009 when it happened.
I bet gbaji can tell you why.
I seem to recall mentioning it once or twice on the forum as an example of something that the media was avoiding talking about. So unless you actually watch/listen to conservative news sources, it's not surprising that you would never have heard about it, or only heard it in the context of "here's some crazy conservative conspiracy theory we can all laugh at and dismiss". It was basically a bunch of liberal journalists who would coordinate their stories so as to maximize the impact of ones they wanted told, while minimizing the impact of those that didn't jive with their political leanings. Which, by itself, might only be of mild concern except that there were a number of liberal political operatives on the list as well, giving rise to the suggestion that the journalists on the list were essentially helping to manipulate public perception of political events to aid specific political groups and candidates (all liberal of course).
It was a big deal among conservatives because we had long suspected some kind of collusion among liberal journalists. It was just too obvious when nearly every major news outlet would all take the exact same take on a given story on the same day, almost like they were sharing notes before writing their editorials or stories. The list showed that at the very least, they were doing precisely that. And while it's nearly impossible to prove, it opens up the possibility that they were deliberately orchestrating the appearance of various stories in order to maximize their impact (or minimize the impact of some other story). One guy writing an op ed about something doesn't have much impact. But when 10 different journalists from 10 different outlets all choose to write an op ed with the same opinion on the same issue within a few days, it creates a story about the op eds, and suddenly that viewpoint is being discussed as news before a broader audience. It's how you launder opinion into the appearance of fact. A news show can't (in theory) just present opinions, but they can do a story about opinions. So if you can get enough buzz about some op ed, you create an excuse for the news to cover it, and now most viewers will give greater weight to the opinion itself because it was on the news instead of just in an editorial.
And when those opinions are being pushed by political policy, you've got a potential scandal. But of course, no one covered the story. Surprise!