Search engines rank the pages according to a variety of (hundreds) "signals", some of which are global (PageRank, ...), some "local" (local link structure, page quality, ...) and some measuring the relevancy of the page for the query (BM25, ...).
All these signals are blended together usually with a function which is regressed using some machine learning algorithm, to fit human judgements and (possibly) click data. Look for "learning to rank" on Google Scholar for details, there are papers by Google, Yahoo and Microsoft.
Search engines rank the pages according to a variety of (hundreds) "signals", some of which are global (PageRank, ...), some "local" (local link structure, page quality, ...) and some measuring the relevancy of the page for the query (BM25, ...).
All these signals are blended together usually with a function which is regressed using some machine learning algorithm, to fit human judgements and (possibly) click data. Look for "learning to rank" on Google Scholar for details, there are papers by Google, Yahoo and Microsoft.
Google itself admits that PageRank is not very relevant (http://sites.google.com/site/webmasterhelpforum/en/faq--craw...):
> [...] worry less about PageRank, which is just one of over 200 signals that can affect how your site is crawled, indexed and ranked.