From the International Herald Tribune (link):
To her fellow students, Hu Yingying appears to be a typical undergraduate, plain of dress, quick with a smile and perhaps possessed of a little extra spring in her step, but otherwise decidedly ordinary.
And for Hu, in her second year at Shanghai Normal University, coming across as ordinary is just fine, given the parallel life she leads. For several hours each week she repairs to a little-known on- campus office crammed with computers, where she logs on, unsuspected by other students, to help police her university’s Internet forums.
Once online, following suggestions from professors or older students, she introduces politically correct or innocuous themes for discussion.
See also the previous CDT post on this subject: “Reports on Internet censorship from Chinese cyberspace” (link).