In August, Facebook claimed of owing Google's social product documents, but the official details about the plan were only shared on Sep. 14th, during Google CEO Eric Schmidt's press conference. Here's what Mr. Schmidt said responding to a question:
Our view of social is a little different than what everyone has been writing. we want our core products to get better from social information. The best thing that could happen is if Facebook opened up its network and if we could just use that information…Failing that, there're other ways in which we can get that information.
We're trying to add a social component [to google's core products] to make them even better. With your permission…and knowing more about who your friends are, we can provide more tailored recommendations, search quality will be better.
A reasonable expectation [of launch] will be the Fall.
Watch the part video immediate below relevant to social, and the second below full press conference video: