gyppo - 10:28 pm on Jan 29, 2013 (gmt 0)
I see this in my particular niche, we present the information on the landing page - which may cause a user to get what they want & bounce. Competitors often will hide the information & need an action to reveal it - sometimes opening in a new window (to avoid users going back to SERPS in the old one).
Not convinced Google treats this how I think they do, but it would make sense to say:
"If user x goes to site a then comes back to Search in some form & refines their query to go to site b then does no other queries" Site b could be more valuable for that given query.
I don't think Google would look at time on site or pages per visit as this can be easily gamed (unlike user intent).