Like others have said its not strongly connected. But it is one of the factors for ranking good in the SERPs
In my niche, "Sacramento Wedding DJs" -- there are two companies that are consistently on top of organic SERP: mine (PR 4) and DJ X (PR 0). DJ X got a Google Slap because he BOUGHT many of his links in Paid Directories where there are too many "porn" or "spam" links. They knocked him down to PR 0 last year --- yet he continues to shine in the SERP. PR has NO EFFECT on SERP!!!
I agree with you. But I want to clarify that TOOLBAR PR does not effect SERRP's, but ACTUAL PR does. My site was a toolbar PR6 at one time, and for the last 6 months a PR3 because Google slapped my wrist for selling advertising on my site and not using rel=nofollow. My positions in the SERP's increased dramatically after the update that lowered my Toolbar PR. Why? Because ACTUAL PR (only Google knows) and toolbar PR are completely different. My actual PR increased which helped in the SERP's.