Google has threatened to stop operating their search engine in China,
citing cyber attacks on private email accounts of Chinese human rights
activists, and the Chinese government's mandate that they censor
information on certain topics. These censored topics, which result
in a search coming up with no results, include the Dalai Lama and the
Tienanmen Square massacre. See the New York Times article here:

http://www.nytimes.com/2010/01/13/world/asia/13beijing.html?ref=global-home