Today's New York Times discusses potential differences between the commission that investigated the Challenger explosion and the one that will investigate the loss of the Columbia:

General Kutyna also noted that there was far more politics surrounding the Challenger investigation than surrounds this investigation. The chairman of the commission, former Secretary of State William P. Rogers, was told by the White House that whatever he did, he should make sure that NASA emerged in one piece, and that the shuttle program went on.
Mr. Rogers, who died early last year, did exactly that, but his mastery of the ways of Washington — from handling Congress to the art of the news leak — meant that he also made sure NASA was forced to clean house.

I am probably the least qualified person in the blogosphere to talk about the space shuttle, but people far more knowledgable than I argue that NASA did no such housecleaning in the wake of the Challenger's destruction:

Will NASA whitewash problems as it did after Challenger? The haunting fact of Challenger was that engineers who knew about the booster-joint problem begged NASA not to launch that day and were ignored. Later the Rogers Commission, ordered to get to the bottom of things, essentially recommended that nothing change. No NASA manager was fired; no safety systems were added to the solid rocket boosters whose explosion destroyed Challenger; no escape-capsule system was added to get astronauts out in a calamity, which might have helped Columbia. In return for failure, the shuttle program got a big budget increase. Post-Challenger "reforms" were left up to the very old-boy network that had created the problem in the first place and that benefited from continuing high costs.

Perhaps Rogers' "mastery of the ways of Washington" included the ability to make everyone think that NASA had in fact cleaned house, regardless of the facts...