From the WP: In China, Would-Be Protesters Pay a Price.
Summary of the article: China made a lot of noise during the Olympics about how it would allow peaceful protests in three special zones. A total of 77 applications were made to protest; none were actually approved. Those who didn’t withdraw their petitions quickly enough are now in jails, mental hospitals, and so on.
An interesting, if little-known, fact is that China’s laws guarantee absolute freedom of speech. However, they don’t guarantee freedom after speech.