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Google’s foray into the world of social search is now live.As we wrote last week, Google social search pulls in results from your friends alongside conventional results. If you’re thinking about visiting Brazil, a traditional search might turn up hotels, tourism agencies and restaurants. But in social search, blog posts or tweets about the trip from friends might turn up at the bottom of the search results page. It pulls in contacts from Twitter, Friendfeed and Gmail.Conspicuously absent from the list is your Facebook network.But really, Google already has it (or at least the public pieces of it). Facebook’s public search listings randomly generate photos of eight random friends. Crawl it enough times and presto! You have a rough social graph. (Even academics from Cambridge University have done it.) Of course, it lacks the richness that Facebook’s social graph data can deliver, because Facebook knows whose profiles you look at frequently, whose posts you comment on and “like”, and whose photos you end up in.Still, Google has some of that in Gmail if you’re a religious user. For those of us who do use Google’s e-mail service, the company knows our closest and deepest contacts because it has years of lengthy personal e-mails and knows who we write most often. By comparison, Facebook knows our weaker ties, as people have about 130 friends on average and use it for more constant and shallow contact.It’s unclear why Google isn’t upfront about the Facebook data it has. I’ve asked Facebook a few times if they’re aware of Google’s capabilities but they haven’t commented.Perhaps it’s because Facebook’s deal with Microsoft to feed public status updates into Bing was non-exclusive. So the door is open to a Google-Facebook public update deal in the near future.Now think about all of those pieces combined if that deal happens: Facebook’s public status updates and shares, a rough social graph from Facebook’s public search listings, Gmail, Twitter and FriendFeed contacts.The old truis