It was being discussed in the past, but last night I actually saw this feature on Google.com live while making search for certain keywords. It is more important to see this feature live in action urself to decide whether it is useful or not.
Everything looks perfect from White Hat
SEO viewpoint, but if Google is planning to use this data to decide future rankings of your site then it could be a big big problem.
It will only open new doors of SPAMMING for BLACK HAT
SEO's as they will work hard to artificially manipulate search results.
There are evidences that Google could be using traffic log data from Google analytic and from within Google toolbar to decide which websites should rank on the top #1 slot and which one on Pages 5-10 (approximation).
If this feature is synchronized with the actual ranking algorithm then it will create whole lot of BLACK HAT
SEO opportunities. Most of the search engine users will have little idea about the real functionality of this feature, whereas most of the BLACK HAT
SEO's will explore every single BLACK HAT opportunity to pull down competitor sites.
I can only wish that Google does not use this data to manipulate rankings ( unless and until the site is really bad with plenty of spam content).