The Google+ Button is another social signal that Google is not using, but it looks like authorship is becoming a new ranking signal.

The Google +1 Button Has No “Direct Effect” On Rankings, But…

Matt Cutts recently said that they are not using Twitter, FaceBook or Google Plus for ranking signals.

This does not mean that Google has given up completely on social networking signals. I think they will continue to try to find an effective way to use social networks, but they have not been able to make that work thus far. It does, however, mean that everything you hear about the importance of social networking signals to ranking results is currently nothing more than misguided speculation.