"Not only this but take PR for example, getting a link from a high PR page used to always be valuable, today it?s more the relevance of the site?s theme in regards to yours, relevance is the new PR." I think this is quite interesting. We've always heard Google harp on about relevancy but i'm starting to believe that Relevance>PageRank is now the case. Think about the recent weight on contextual links. Think about how sophisticated Blog networks are and how much easier it is to get a high PR in recent times. Five years ago a PR5+ link cost a lot of money, it is now much easier and cheaper. But to get a link on a site 100% dedicated to your niche is still quite difficult. I think there are many more pieces of evidence which point towards a relevancy dominated algorithm these days.