Now we know what Facebook is building: A better internal search system.

Speaking at a much-hyped event at Facebook HQ, founder and CEO Mark Zuckerberg announced a raft of improvements to "graph search" — that is, the ability to search within your social graph for specifics.

The search improvements involve the ability to ask questions in regular English, such as "which of my friends live in New York?" The search is now intelligent enough to rank your friends based on how much interaction you've had — so that closer friends will appear higher up the results list.
It can also search based on stories or photos you've Liked. One example Zuckerberg offered: the site can now display which of his friends have Liked the HBO show Game of Thrones. You can search for people who Like multiple products or services, which seems likely to be a bonanza for marketers.
Photos can also be ranked by which have the most Likes, based on the people most important to you in your Friends list. And one of the most useful use cases appears to be searching for local businesses that have received a thumbs-up from friends (and their friends).

Graph search starts today in beta, and will appear as a large blue search bar at the top of your Facebook page. You can sign up for the beta — or rather, join the Waiting List for a beta invite — here. Zuckerberg was careful to emphasize that Graph Search is a new and limited product. For now, it will focus on four areas: people, photos, places and interests.