Page rank question.

[Infopub]

Just wondering if there is an updated document anywhere that contains details on how google determines page rank?

Is it soley based on who links to you? If so, what if I have 100 sites linking to be and they all have a PR of 5, does that mean my PR will become 5?

I am trying to figure out how this is determined and why some of my sites are 1,2,3 and others are 4,5,6

thanks

[WebGuerrilla]

You can find quite a few Pagerank papers (both new and old) here. [google.com]