Interestingly it's partially the same issue - the directory servers have static IP's. ISP's are simply blocking traffic to these directory server IPs. Without access to the directory servers, can you still use Tor?
Also see above article for thoughts on how to circumvent this mode of censorship.
Tor has a network of unpublished bridges it provides via offline methods in high risk countries. You can also request unpublished bridges via email [1]. Pluggable transports [2] allow your tor traffic to look like Skype or SSL. These tools combined allow most of the "noble use cases" of tor to operate without being hunted down.
The last update I heard is that the GFW does active probing to detect Tor bridges and relays. That is, there are computers inside China that are triggered by something, which then actually speak the Tor protocol to an IP to check if it's capable of subverting the firewall. If so, it gets blocked.
There isn't really any way around that which scales, which is why Tor is basically a non-entity in China right now. Everyone I know from the west who spends time in China just uses commercial VPN services, not Tor.
Interestingly it's partially the same issue - the directory servers have static IP's. ISP's are simply blocking traffic to these directory server IPs. Without access to the directory servers, can you still use Tor?
Also see above article for thoughts on how to circumvent this mode of censorship.