Every major search engine (Google, Yahoo, Bing, ~Ask) uses a form of "PageRank" for their rankings. That is to say, all major search engines use the a graph as

Every major search engine (Google, Yahoo, Bing, ~Ask) uses a form of "PageRank" for their rankings. That is to say, all major search engines use the a graph as their primary ranking metric (other than relevancy, obviously). I don't know how the patent plays in, but its fair to say "the cat is out of the bag" that a weighted link graph is (currently) the best way to algorithmically determine a given website's authority. Disclaimer: I don't work for a search engine, but I am an SEO.