Also there is a book on the subject Google's PageRank and Beyond http://books.google.com/books?id=KsHTl_2Pfl8C
Other interesting articles: THE $25,000,000,000∗ EIGENVECTOR http://www.rose-hulman.edu/~bryan/googleFinalVersionFixed.pd...
How Google Finds Your Needle in the Web's Haystack http://www.ams.org/samplings/feature-column/fcarc-pagerank
The Google Pagerank Algorithm and How It Works http://www.cs.princeton.edu/~chazelle/courses/BIB/pagerank.h...