Wikipedia prides itself on openess and the sharing of information.  The site usually leaves the policing to the public and it's fairly accurate considering that they allow anyone to add or edit articles.  But recently, in a 10-1 ruling, the site’s arbitration council voted to ban users coming from all IP addresses owned by the Church of Scientology and its associates, and further banned a number of editors by name.

This punishment is the result of repeated and deceptive editing of articles related to the controversial religion.  "Self-serving Wikipedia edits are hardly new. Wired.com readers pulled in an award for discovering the most egregious Wikipedia whitewashes by corporation and government agencies, but this is the first time the site has taken such drastic actions to block those edits."

via Wired