wordpress, blogger(blogpost), tumblr are also banned 

The system of firewall of China is called the GFW. Google it!

( http://en.wikipedia.org/wiki/Internet_censorship_in_the_People%27s_Republic_of_China#Technical_implementation ;)

famous websites like Twitter, Facebook, part of Google's services, Youtube, also thousand of blogs.

法輪功

台灣政府 之網頁

And what happens if you , say , sneak your way into those websites using Probably Repudiatable Online eXtrication sYstems (if you catch my drift) ?

A lot