You know about the released Wikileaks cables, right? If you visit certain torrent sites, you may even have them on your computer.
Well, some very witty people at the ACLU decided to find out what would happen if they asked for 23 of those cables via FOIA. Surprise: Only 11 were released
-- in redacted form. The censored bits focus on Gitmo and the CIA rendition flights over European airspace.
If the stuff is out there already, why would the administration attempt to hide it? Censorship of already-released material makes the government look foolish.