Facebook began allowing users to control who would be able to see specific posts they made. The default categories were public, friends of friends, and friends. The update also allowed Facebook users to share content with a specific list of friends based on “friends lists” which was launched a few months earlier in December of 2007.
This update adjusted content seen in the News Feed by users indirectly as content that may have been shown to a user would be restricted based on the settings of each post.
More Information / Press
Official Blog Post: Announcement: Facebook Updates Privacy Controls