Social Media not involved in Free Speech?

A code of conduct was signed between Google, Yahoo, and Microsoft to protect free speech and privacy. This has been known as the Global Network Initiative. However, since the shenanigans in the Middle East, it's a bit of shock that Twitter and Facebook are absent from this pact. To give a bit of idea of what this pact does, Microsoft has shut down a blog by a Chinese journalist who worked for The New York Times, Google has introduced a censored search engine in China, and Yahoo has turned over data that has led to the imprisonment of Chinese activists.

They are still trying to get in cahoots with Facebook over this project, and Twitter has declined to comment.

Source: http://www.nytimes.com/2011/03/07/technology/07rights.html?_r=1&hpw