How did I never hear about this? According to a journal article I just read (Moody, Kim, "Covert Censorship in Libraries: A Discussion Paper," Australian Library Journal 54), Michael Moore's Stupid White Men was originally set to be released on September 11, 2001. Needless to say, the publisher (Harper Collins) asked to postpone the release even though the books had already been printed, and Moore agreed. When Moore contacted them some time later to see when the book would be distributed, Harper Collins demanded they be allowed to redact parts of the book, such as the criticisms of George W. Bush. When he refused, they said they would pulp the books.
Thankfully, the ALA pressured Harper Collins to release the book, which they eventually did.