What Social Signals Do Google & Bing Really Count? by Danny Sullivan at Search Engine Land is a must read by all. Danny interviewed Google and Bing on how social signals, mostly Twitter and Facebook, impact their ranking algorithms.
In short, both Google and Bing do use some of these signals in their organic web search ranking algorithm,
Let me highlight some of the questions and answers:
There are two WebmasterWorld threads now dissecting this interview.
Tedster commented:
