Microsoft and Facebook have announced a new partnership that brings “Like” data and profile search to Bing. The deal marks a big leap forward in social search and also represents a new advantage for Bing –- which Facebook CEO Mark Zuckerberg declared the “underdog” in search during today’s press conference -– in its quest to take market share from Google.

Starting today, Bing users now get an experience that’s customized using Facebook Instant Personalization. For now, that means searches (where appropriate) will feature a Facebook module that shows you what your friends have liked as it relates to that search, as well as a smarter people search results.

The Bing and Facebook teams offered a few examples of how that might be useful during today’s press event: surfacing restaurants that your friends like, pulling in movie likes from IMDB or articles that have been shared about a car you might be eyeing. With the like button now being used by more than two million sites and Facebook passing 500 million members, there’s now enough scale to make that type of data surface on a regular basis in search.