Well - just to confuse the issue for everyone
Maybe I ought to explain some differences here as a lot of people use two things interchangebly that really aren't the same thing
PR - as measured by the google toolbar and next to the ranked listings in the Google directory are not a visual display of a web pages "Page Rank" - they are a measure of googles little having fun wit webmasters toy
Page Rank - This is what Google really uses in its algorithm to decide where a web page should rank in the listings (SERPs) - and is based on over 100 factors from on-page things to who links to the page etc. It is also the complete basis of the whole mathematical model that the boys from Stanford wrote up back in their college days and is now called Google - and will always be the most important thing for ranking - however the importance of one of those over 100 things can be adjusted in the algorithm if Google sees fit - and they have proved that many times.
Hope I didnt confuse the issue too much