Last fall Google began experimenting with a new feature called Social Search, and we called it a big chess move against Facebook. Today Google Social Search is opening up in beta for all Google users. The experimental feature will surface search results from the social streams (bookmarks, blog posts, photos, etc.) of a user's contacts on services like Gmail, Google Reader or Twitter.

Social Search still doesn't have a super-prominent place in the Google Search results pages, but make no mistake: This is a very big step. What's your portal to the Internet: Google's algorithmic search of the Web at large, or your social circle of people on Facebook? That's the battle for the future that Google and Facebook are waging now, and Google Social Search is a big move. Facebook search is nowhere near as good.

You may need to go to Google.com/experimental to turn on Social Search and you should try an image search once you have. It will be turned on by default for an increasing number of users over the next few days. The feature requires you to be logged in and discovers your friend connections through your Google Profile.

Last week we wrote about how social networking is fast approaching the importance of online of search in terms of Web traffic. One vision of the future, though, has posited that social and search won't remain separate forever.

Do you want to have your questions answered only via your friends and their online content? No, probably not. But do you want to have your questions answered without the input of your friends and their trusted content? You probably don't want that either. Google Social Search is a nice combination of search and social. Facebook's search is terribly weak in comparison. That's where the real competition is, not between Google and Bing or Yahoo.

One interesting caveat, of course, is that most people have friend networks on Facebook, not in Gmail or Google Reader. Your Facebook Friends aren't included in Google Social Search, as far as we can tell. Update: Limited information from Facebook may be included in Google Social Search if your friends have associated their Facebook profiles with Google Profiles. But after chasing the Google Social Search team around on the phone for 15 minutes and just getting a PR-answer about this, we're left to conclude that the rivalry is as heated as we originally reported. Murali Viswanathan, Social Search product manager sent this by email: "If someone links to their Facebook account from their Google profile, Social Search may surface that user's public profile page. These are the same public profile pages already available on a search of Google.com and other search engines today."

Give it a try and let us know what you think.