From March 16, some of the most influential University BBS (Bulletin Board System) in China... have been restricted to users with an IP inside the university only. That means public users, who make remarkable contribution to the conversation, are not able to access these BBS any more. Before, these BBS hosted very active public forums and attracted millions of registered visitors inside and outside the university. Protests have been organized around Chinese universities. People are calling it an insult on the freedom of speech, but soon their posts were deleted and their voice stifled by university administration.
In response, students have fought back in the Chinese blogosphere, getting the story out. Moreover, they've been using the tag "SMTH" (after the url for the Tsinghua University Bulletin board, smth.org) for images and text on sites like Flickr, furl and del.icio.us. The tags allow people to quickly and easily access content regarding the clampdown of information in an environment where getting information can be problematic.
Students protest restrictions on most influential BBS - China Digital Times