About Facebook Privacy

Using the Timeline feature of Google search, I tried to search the changes made to the Facebook privacy settings across time:
Before ~April 2010: Users had the option to allow each separate application access to your data.

April 2010: The 'Instant Personalization' feature was launched. This was enabled by using the Open Graph API set (Ref: http://www.youtube.com/watch?v=jaWSvkd37TQ)
Mark Zuckerberg's argument was that these changes had no effect on the then current privacy status. This is true. But, it allowed your details to be actively displayed to your friends rather than they having to browse to your profile to gather this data.

Late May 2010: After more than a month of intense criticism, Facebook allowed simpler privacy controls. (Ref: http://www.youtube.com/watch?v=Q_o4MvgiMHg). This enabled a user to opt out of the Instant Personalization' feature. This continues to date.

The reason this feature got so powerful was that relevant information about your friends were put up at places where they made the sense most (rather than remain static in their profile pages). Also, for the website, all it involved was a single code snippet and suddenly it was Facebook-enabled. Each 'like' translated into a post on a profile which was further liked by others. Content providers totally 'liked' this idea.

Also another bit of news, Facebook Connect was something that was launched in Late 2008. It allowed a unified login to websites. The Open Graph API superseded the Connect. Though, I guess, there are still a few websites that havent migrated from FB Connect to Open Graph.