Yaman Akdeniz has recently published a superb report for the OSCE on Turkey and Internet Censorship (press release | full text pdf).
Ironically, Yaman Akdeniz and his co-author Kerem Altıparmak have themselves been the subject of legal threats aiming to silence their criticism of Turkish internet censorship. Fortunately their book Restricted Access: A Critical Assessment of Internet Content Regulation and Censorship in Turkey (2008) is still available.
The image above is from Richard Dawkins' website, which has been blocked in Turkey since September 2008.
(Via Chris Marsden.)