From the article: "Chinese people can write the most vitriolic blog posts about even the top Chinese leaders without fear of censorship, but if they write in support of or opposition to an ongoing protest—or even about a rally in favor of a popular policy or leader—they will be censored."
That is interesting. I am glad someone has discovered this. So perhaps the way to organise a protest, is to use secret messages coded in the form of vitriolic comments. Eg, "Mao Tsedong is an idiot" = Meet at Tiannamen Square.