Three years ago, Google, Yahoo, and Microsoft signed on to a code of conduct designed to protect free speech and protect privacy online. The Global Network Initiative was crafted at a time when the companies were taking big PR hits for censoring search results in China, turning over information about users to foreign governments, and generally making life more comfortable for big governments.
The code of conduct says that companies must try "to avoid or minimize the impact of government restrictions on freedom of expression" and protect user privacy when demands by government "compromise privacy in a manner inconsistent with internationally recognized laws and standards."
But there is wiggle room. The companies can still share data or censor results as long as they disclose it.
Tellingly, no one else has signed on, including Facebook or Twitter. This matters - a lot - because when the internet is really being used as a tool against oppressive regimes, THOSE are the companies that are being employed. Yahoo made no difference in Egypt, where a father named his daughter Facebook.