tedster - 4:28 am on Sep 11, 2011 (gmt 0)
Here's a link for the article - which is now four years old. [seomoz.org...]
By now, I'd say it's foregone conclusion for many that Google is using behavior data - just where the data comes from is the question.
I suspect that it's harder to manipulate these days than it was in 2007. The safeguards on false clicks on Adsense, for instance, have taught Google a lot about how to find manipulative patterns in any click stream.