Is the Great Firewall of China not effective enough?
I suspect this is motivated by performance concerns. The overhead of the centralized filtering they do is massive, and a friend living in China tells me that it hurts net responsiveness badly. Since the Chinese government already seems to have decided a while ago that it's only interested in preventing casual access to subversive material and doesn't care about anyone determined enough to bother connecting through a…
It's already got a name -- hacktivism -- and it's happening in places like the Citizen Lab (U of T) already. If you're not familiar with the Open Net Initiative, it's worth a visit to http://opennet.net to find out what's being done today.