In China, the great firewall blocks bitcointalk and presumably Bitcoin nodes. It is easy for them as they have the firewall in place already. It is impossible to block it completely but it can cause some inconvenience at the least.
and im sure chinese goverment never plan to do it
They don't block the exchanges though.
try it
http://www.greatfirewallofchina.org/index.php?siteurl=bitcoin.com
http://www.greatfirewallofchina.org/index.php?siteurl=forum.bitcoin.com