Earlier in 2012, Bing launched a new search feature called Bing Linked Pages, which allows web pages within it's index to be "linked" or tagged to people using a relationship indicator. This search meta data shows the relationship of content between individuals--friends and yourself.
The Linked Pages feature was just renamed Bing Tags--a shorter descriptor that has the same capabilities as before.
The goal of the search application is to make search results more personalized and thus more useful to users. It's connection with Facebook seems to attempt to draw a smoother transition from the social platform to web searches--a type of fluidity from one to the other.