I assume that you are asking about a possible system in which someone would decide which facts the media would be allowed to access and which it would not be. This might be a system that would handle cases like the Wikileaks case. The system would decide which leaks the media could and could not report. Such a system would be very difficult to manage given the number of media outlets in the United States. The system would have to be tremendously big to handle all of the demands.
If we were to put such a system in place, it would have to be made up of experts in two main areas. First, it would need journalists. They could help to determine what sources were necessary for a story and how much could be hidden without taking away from the value of the story. It would also need social scientists such as political scientists. They would need to assess the relative importance of exposing the information and they would need to assess the possible harm to the country from such exposure. Lawyers might be needed as well to rule on legal issues, but this would depend on what the laws that created these bodies looked like.
It is almost impossible to imagine this ever happening, but that is how I would put together a non-governmental group to do this job.
Government and media mainstream media are more closely connected tha you might think. Most governments understand tha if you control the information going out, you control the people. Propaganda was not just a tool of Hitler or Stalin.
its not difficult to see the evolution of media in the US as it moves ever closer to singularity. More and more media outlets are owned by fewer and fewer people. This is evident in the same stories mirrored by the main news outlets and their many subsidiaries. It is not a huge leap to say the masses are being manipulated, or at least the potential for manipulation increases with this trend.
An oversight advisory board that determined the "truth" or "facts" could only exist on a superficial level giving an illusion of morality or fairness. After all, the media was a creation of goverment and will forever be linked.