Since 1982, many libraries in the United States have dedicated the last week of this month to recognize how fortunate we are to have the freedom to read. The American Library Association  observes Banned Book Week from September 26th through October 3rd, 2009, and encourages us never to take for granted our freedom to enjoy literature, information, and ideas.
Many of the books we're used to seeing on library book shelves were at one time considered unsuitable. They were "challenged" based on political, religious, or sexual objections. Sometimes books are challenged or banned because the cultural standards accepted when the book was written no longer seem appropriate.
It's interesting to note when and why a book was challenged or banned. Caligula tried to ban Homer's The Odyssey  because it "expressed Greek ideals of freedom". Gulliver's Travels  was pronounced wicked and obscene in Ireland (1726). Lewis Carroll's Alice's Adventures in Wonderland  was banned in (1931) China on the grounds that "animals should not use human language." Ray Bradbury's Fahrenheit 451 , THE novel about book-burning and censorship, was itself censored at the Venado Middle School in Irvine California in 1992; students' copies had many words (mostly mild profanities) blacked out. In 2006 an interesting scenario occurred when Iran's Ministry of Culture announced that, based on the request of three Christian clerics, no more versions of The DaVinci Code  would be published.
If you're interested in finding out more about recent book bannings in the United States, Google has a map of 2007-2009 Book Bans and Challenges here .
Image courtesy of pollyalida