According to author Cory Doctorow in a post at Boing Boing, Wikipedia, the encyclopedia that can be edited by anyone has been unblocked in China. Unlike Google, Microsoft and Yahoo, Wikipedia refused to censor itself for use in China. It seems that China has seen more value than potential harm in allowing it to be unblocked. However, readers in China report problems getting to the Chinese language version and into articles on certain subjects.
That's predictable enough -- but it means that Beijing is now stuck playing cat-and-mouse with Wikipedia, having to ferret out every potentially sensitive page and update its filters accordingly. If MSFT, Yahoo and Google followed Wikipedia's lead, we could force Beijing to devote ever-escalating resources to this effort, a denial-of-service attack on its censors.