Google has launched Social Search -  an new tool within its Google Labs feature that was unveiled last week - which allows web users to search the internet for content relating to people in their social circle.

The Google Labs page explains that with Social Search, you "sign in to Google and do a search. If there's relevant web content written by people in your social circle, it will automatically show up at the bottom of your search results under a section called 'Results from people in your social circle'."

Marissa Mayer, Google's vice president of search products told PC Advisor's sister publication Computerworld:"We came up with a way to have social networks influence your search results".

"If you're signed into Social Search, you get content from your friends.

"There's a huge amount of data on social networks," she added. "Think about social networking and it's really about people as sensors. Is the power out over there? How is the snow there? Are the speakers good at this conference? If I can search this massive amount of data, a user can find out what it's like over there right now. That's very exciting."

Google announced Social Search last week at the same time it disclosed that it had inked a real-time search deal with Twitter . Mayer said the two announcements are related in that users will eventually see Twitter posts , or tweets, in Google search results.

For today, however, all search focus is on the addition of Google Social Search to Google Labs.

Google Social Search is designed to let searches return traditional results along with updates and tweets that their friends and other people they follow on various social networks have posted. For instance, a user might want to buy a specific car.

They can search for information and reviews of the car on a regular search engine and then use Social Search to find pertinent posts from their friends and colleagues.

Dan Olds, principal analyst with The Gabriel Consulting Group, said the experimental new service has the potential to make social networking more useful.

"With it, you can mine your own circle of contacts for information, whether it's for recommendations on a handyman or a pointer to a company that's hiring," said Olds.

"It will also encourage people to expand their networks, since more friends and a wider range of friends mean more useful information."

Olds noted that Google Social search is a good example of networks becoming more valuable as they get larger.

"Let's say that I'm looking for a new LCD TV," he added.

"I'm researching models on the web and happen to see some results pop up in my Social Search. Out of all of my contacts, it's pretty likely that a friend or acquaintance has bought a TV in the last year or so, and they're chock full of useful advice. The bigger my network is, the more potentially useful information it contains."

How will Google know who your friends are?

Mayer explained that users will be able to fill out a Google Profile, which would be used to link to friends on Facebook , LinkedIn, MySpace and other social networks. If they use Gmail, Google will have access to their contacts.

"You opt in to using Social Search and then we look at who your friends are and what content they might be publishing," she said, adding that Google is aware of people's privacy concerns.

"We tell you which data source we used in order to find that friend. We're doing our best to be transparent about how we found the relationships. And people have the choice of whether they want the feature or not."

Google did not disclose how many people have so far signed up to try out Social Search.

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See also: Google tweaks Custom Search's layout and results