Yesterday, more sites were blocked, including Chinese microblogging service Fanfou.com, but since it's a local site, its blocked in a different way than other sites. The sign on the site merely says the site is "closed for maintenance;" I'm guessing the Chinese authorities have expressed a sudden interest in the health of Fanfou's servers. Social network Xiaonei.com, as well as dictionary site Wordku.com have suddenly been closed for maintenance in a similar manner.
We've also reported that Twitter can be accessed through third party clients such as Seesmic Desktop or Tweetdeck (Loic le Meur even joked about the Chinese government driving the growth of Seesmic Desktop), but unfortunately, that no longer seems to be the case. Initially, Facebook was one of the rare big social networks that avoided the block, but according to latest tweets, even Facebook has gone dark now (*edit: some of our readers claim that Facebook hasn't been blocked).