Rebecca MacKinnon writes in the Wall Street Journal:
The “Great Firewall,” the common moniker for China’s filtering system that blocks various Internet addresses and keywords, really only pertains to Internet sites and services hosted on computer servers outside China. Inside China, companies that host Web sites, blogs and chat rooms are held responsible for objectionable content posted on their services. All of China’s blog-hosting services, YouTube-style video sharing sites and the like hire entire departments of people to flag and delete things that may get them in trouble with the government authorities who could revoke their business license.
This context is key to understanding the wide-ranging conversations, many of them political, that are now happening on Chinese blogs and chat rooms. There is indeed a vastly larger space for public discourse on matters of public concern than existed even a few years ago. But that space still has limits. Chinese Web users now experience a more targeted and subtle approach to censorship than before.