I just finally got around to reading last month's Mother Jones' article "The Lie Factory," and I think it's the best article I've read on how the intelligence distorting process worked. It's comprehensive but concise. It does a good job of untangling the connections so you can see them:
http://www.motherjones.com/news/feature/2004/01/12_405.html
And don't miss this chart, which is one of the best parts:
http://www.motherjones.com/news/feature/2004/01/12_400.html
Unfortunately it probably shows exactly where the bog is where the intelligence investigation will probably vanish. When you look at the flow chart, what you see is the CIA and DIA feeding decent enough information (except about chem and bio) into special Whitehouse-built cells in the Defense Department, which it is then distorted, mixed in with other "intelligence" from Chalabi informants, the resulting slurry fed to the White House, meaning Cheney, before or after it goes through Feith and Wolfowitz.
The problem is, Defense is neither quite the White House nor quite the intelligence community. They probably won't get investigated because they don't count as the intelligence community. And if they do, it will be easy for them to obscure where the fault lies by pretending they are were part of the intelligence community.
So oft-bruited question of whether Cheney tried to intimidate the CIA directly by visiting is kind of a red herring. He might have, but he didn't have to. His boys in defense were taking the CIA info, slicking and dicing and cooking it, and feeding him exactly what he ordered directly to his office. But in such a way that both he and the CIA can say they didn't do it.
Michael