These white cards will appear in your mobile feed soon, where they'll dig through what your friends thought of the experiences you're having now.
Last week, Facebook began testing new features you may spot within the Facebook iPhone app. They're called Context Cards, and whenever you check in to a place a la Foursquare, or mention that you're reading a certain book, these white cards being tested with some users might pop up in your News Feed to tell you what your friends think about your taste in restaurant or the way that book ended.