I am in China and have probed the Great Firewall. As news reports state, I have been able to access the BBC website in English. However, a Wikipedia inquiry to Tibet results in the denial of the page. If I run VPN to the University of Manchester, then I can access all the denied websites.
I tried to run a test on whether the rumour that elgoog (google mirror) evades the firewall but unfortunately it appears to be down for repair. Try http://www.newscientist.com/backpage.ns?id=mg18424782.700 for information on elgoog and the firewall.
Jing Jing and Cha Cha are watching you.
http://en.wikipedia.org/wiki/Jingjing_and_Chacha