Search for “Tiananmen Square” on Google.com and the first result that comes up is a Wikipedia entry: “Tiananmen Square protests of 1989.” Other top results include a BBC story on the “massacre” and references to “bloodshed”. Now try the same search at Google.cn, the portal for Chinese users. Back come pages largely of use to tourists. There is a small chance that Chinese surfers only want handy travel hints and have no interest in one of the biggest events in their recent history – but it is more likely that those other pages have been censored.
http://www.guardian.co.uk/leaders/story/0,,2210420,00.html