Blogoscoped has a post called "Google-powered Social Site Shuts Down "Sensitive" Groups?". Apparently, 'sensitive' groups in social networking site, Tianya have been closed down.
Posted below is an example of a Tianya group, called "Google Fensi" that was shut down recently.
Apparently, "Google in China, is actively shutting down groups dealing with "sensitive" topics such as Falun Gong, or certain political discussions. Furthermore, you can't even create groups dealing with e.g. politicians Hu Jintao or Jiang Zemin in the first place."