Facebook Chairman and Chief Executive Mark Zuckerberg introduces Graph Search features during a presentation January 15, 2013 in Menlo Park. - 

Tuesday's surprise announcement from Facebook was not the mobile device that some observes thought the company was planning. Instead, the social media giant announced an ambitious new search feature called Graph Search, that could be a game changer for Facebook.

Graph Search combs through the data your friends give Facebook, instead of searching the web, like Google.

CEO Mark Zuckerberg explained how he and his wife, Priscilla, like to  try new restaurants. But instead of doing a web search through Google, he asked Facebook.

"I put in this query, looking for restaurants nearby that my friends have been to. You can see right here which friends have been to each of the restaurants, which ones have liked it," Zuckerberg told a press conference at Facebook's Menlo Park, California headquarters.

Facebook is betting its users will prefer those answers over suggestions by random people on Yelp.

"Having results from your close circle of friends is going to mean something for you," says Brian Blau, an analyst at Gartner. If a personalized search means a lot to you, the user, it will mean a lot to advertisers too.

Graph Search is still in the testing stage, and will only be available to a few thousand users.

But Blau says the new search function can only go so far. "The next pocket knife your friends want to buy you know your friends might not have bought any of those things."

And so the random suggestions on Amazon and Google aren't going away anytime soon.