crobb305 - 6:04 pm on Mar 20, 2011 (gmt 0)
I'd say Google is studying USER behavior most of all
Something else that I have observed... On *some* results, when I hit the back button to leave a site, I see the suggestion, "block all results from this website" (the new Chrome feature). I have not seen it for every page I leave, but only on some. Perhaps it is triggered after you leave a site a certain number of times, or on sites that Google considers to be of borderline quality and wants the user to provide feedback?