I was at an SEO seminar recently and was told of some research the speaker had done to determine how page rank was distributed and how it could be managed within your site. In a very simplified version, here is what he said. Page rank will basically filter down from pages linking to your site, so in simple terms, if a page rank 8 site has 1 link from it, the site it is linked to will also be given a page rank 8, 2 sites linking & they will both get PR4 etc. However if you use the nofollow tag on internal links, these links will not pass PR, and the rank will be distributed exclusively to other links from the page. See the diagram below: Thus by using nofollow links to less important pages internal links can be built to favour your most important pages from a PR perspective. Interesting, I thought.
