Facebook just announced a new search tool called Graph Search that is now in beta for a limited number of users. It allows users to search based on information about their friends. A search, for example, for a restaurant will return results based on the likes and interests of the searcher’s friends.
It seems that Facebook is respecting user privacy settings, and basing the search only on what users have chosen to make public. But then again consent is all about context, and users may not have thought about such a feature when considering their privacy settings.
Facebook’s announcement has a section on privacy. If you want more detail CNET has a good article talking about things that the search will look at (such as shared data from apps and tagged photos) and things that we should look at to make sure we are still comfortable with our settings in light of the search tool.