Google Page Rank Explored

1. Page Rank Explained - This site explains pretty clearly how Page Ranking works. The formula you see in there is pretty common and date's back to the original google founders Stanford article.
2. Google Ranking Factors - This site explains google in terms of the DOs and DO NOTs. I really liked this site and found it very useful.
3. WebWorkshop PageRank Explained - This site is very similar to #1, but they did a better job of explaining how to lay out your site with respect to getting the most out of page ranking. The explanation of how links between different pages within your own site was the gem in this sites article.
4. Original Stanford Paper by Google Founders - From what I can tell, the original founders, Sergey Brin and Lawrence Page, go over the anatomy of a search engine. Good publication to reference.