With its new search tool, Facebook is aiming to be more than an online social space -- it wants to be a resource too.
Speaking in broad generalities, Facebook is for fun. It's where you go to procrastinate, to chat with your friends, and to consume media (articles, videos, movies, etc.) that they have shared with you and that has been pushed at you via your News Feed.
Google, on the other hand, is useful. If you need a piece of information -- directions, a historical fact, movie listings, news, etc. -- Google is often your first stop.
For the most part, that division is a pretty good characterization of these two Internet giants' separate spheres. Of course, Facebook is useful in the sense that having friends and staying connected with them is "useful," but it's not a tool primarily for research. Sure, you can ask people for information (movies they've liked recently, or a good Italian place nearby), but the system is not designed to facilitate finding out the answers to those sorts of queries.
With "Graph," the new Facebook search tool introduced yesterday, Facebook is making a play become a bit more useful -- to become not just a place to socialize, but also a place to find out information. Though that is traditionally Google's territory, the kinds of information Facebook can access are quite different than Google's, and, for the most part, Graph shouldn't hamper Google all that much.