Slate published an article named Error Message: Google Research Director Peter Norvig on Being Wrong and a lot of people are talking about his philosophy on Google and him being wrong. Cool!
But he did lay down some tidbits on Google's ranking algorithm. Let me share them with you. One of the more interesting quotes, for me, is:
Yeah, that's always a problem. One way we try to counter that is diversity. We haven't figured out any way to get around majority rules, so we want to show the most popular result first, but then after that, for the second one, you don't want something that's almost the same as the first. You prefer some diversity, so there's where minority views start coming in.
So for the first search result, Google is looking for the "most popular" result to place first. Not necessarily the most relevant or the best match, but most popular. Great, so how about the second result, is that the second most popular result? No! Instead it is a diverse result, something that differs because "you don't want something that's almost the same as the first," Norvig said.
As Tedster points out in the WebmasterWorldthread discussing this, he sees this often and this is where Query Deserves Diversity comes in.
Another interesting quote revolves around real importance of PageRank:
It sounds like page rank uses consensus as a stand-in for credibility. That slippage is hardly unique to Google-all of us use consensus as a stand-in for credibility sometimes-but it can be pretty misleading.