Don't quote me but I think its the PR of the page linking to you is divided by the number of links. So, if its a PR8 with 4 links, then each one would get a PR2 from that link (8/4 = 2). I could be wrong here, but I think it works something like that or at least thats the gist of it.
... and who goes to google.ca? eh? :hehe: