I happened to catch a part of the Rachel Maddow show last night where she interviewed a lawyer reviewing the torture memos, and he said that a lot of the pages that had been blacked out had NOTHING to do with National Security, but were just damning to the administration that ordered it. Basically, the blacked out portions were the parts that covered up the uselessness of the torture, or where the torture hadn't worked (positions they were trying to defend, where the blacked out memo was in direct contrast to their "defense").

They blocked it out to cover their asses.
What a sick, sorry bunch. May they get those asses kicked.