An excellent thread at SEOChat is helping to uncover an uncomfortable phenomenon at Google - sites that rank well are very, very old. While this has been speculated about for many months, these are the first publications of any scale to be released.

Read the thread - Proof Of Search Position Based On Age Of Domain?

Then, check out the great tool for checking the age of up to 10 sites at a time - Find Age of Website Tool. Using this tool and a variety of other factors, I have generated some data about Google's neophobia. Don't miss - Age of Sites & Google's SERPs.