William Flaiz, writing in Search Engine Watch asks Are Rankings Still Relevant?. In that column he reviews some of the means by which Google collects data on our search behaviors:
Every fun, timesaving Google feature you use in your daily activities is feeding Google information about you. And if they continue to "not be evil," your searching experience will likely be more in tune with your lifestyle.But Flaiz's objective isn't to instill us with fear toward what Google knows. Instead, he seeks to convince us that Google's accumulated information may ultimately personalize our searches. The trend he identifies is a decline in the value of somebody else's opinion toward a particular site, and an increase in Google's ability to actually predict that the site contains information that we're interested in finding.