Out in left field...
I read someone once again spouting the old chestnut that the reason no one involved in the hoax has blown the whistle is because of death threats, either from the CIA or some other black bag outfit.
No offense intended to our non-US friends here, but I get the feeling that most of the ones saying this aren't that familiar with life in America. I just think that all those good ole boys in Houston, Huntsville, etc wouldn't all have responded so meekly to death threats, especially after a few beers on the weekend.
If there HAD been a threat-enforced cover-up, the surprising thing isn't that it worked, but that there weren't any reports of fire-fights involving NASA personnel.
Just a random thought...