I think that high PR is not equal to high rankings. For example, some auto site with pr 5 may be ranged higher than other thematical sites with lower pr , but in the Top for the keyword "flowers" it will be lower than a Pr 1 flowers related site.
Really? Despite Google's clear statement? — "Pages that we [Google] believe are important pages receive a higher PageRank and are more likely to appear at the top of the search results." http://www.google.com/corporate/tech.html