Great points Julien - many people automatically assume that a higher
PR will mean top of the list in google, when it's very easy for lower
PR sites to beat the higher ones. As I understand it there are a few more factors other than just backlinks (but I don't know them) although the basic principle is based around that.
also, just to pick up on Julien's point about the toolbar and real
PR. I have seen one of my blogs go from 0 to 3 then 2 then 1 then 0 then 3 again in the space of 2 months. so don't take any notice of the toolbar and stick to making your site user friendly.