This is an excellent page that explains the mathematics behind Google’s PageRank and illustrates it with an interactive diagram. You can arrange a series of pages, link them to each other and see the resulting PageRanks.
After ‘the science bit’ he concludes with this little piece of wisdom that I hope all SEO ‘experts’ actually get to:
How can I use this to drive traffic to my website?
If you take anything from this article take with it the spirit of sharing knowledge. Knowledge is the only type of content that is truly valuable and there should be no doubt that search engines now and of the future will try their best to make sure it ends up at the top of their search results.