I have spent the past half hour wondering what is going on here, and finally understand what this is all about. Facebook has a Year in Review function which will allow you to check out your ” 20 biggest moments from the year including life events, highlighted posts and your popular stories.” Essentially it aggregated the most popular pics and stories you had throughout the year. Simple, easy, and kind of fun to take a look back.
You can check your year in review here: https://www.facebook.com/yearinreview
There is also this from Facebook.
We took the pulse of the global community on Facebook in 2012 to assemble a series of trend lists, chronicling the top events, the most popular public figures, the most listened to songs on Facebook and more. These lists are available on Facebook Stories at FacebookStories.com/2012.