I have had some good gains on newish sites and no change on sites that I expected to change. Anyway my theory: It seems that my sites Google cached on or before 20th Oct have No PR change. Sites cached after 20th Oct have all had changes. Has anyone noticed anything similar???
Toolbar PageRank, for what it's worth, has changed on most of my sites. My main hosting site jumped from N/A to PR4, while another site dropped slightly from PR3 to PR2. I've just checked your theory - a site of mine was cached on the 22nd and it's PR has remained the same. However, I've made few alterations to the outgoing or incoming links on that, or done much SEO on it for AGES so it probably wouldn't have changed anyway. Your theory is interesting, although I no longer really think PR has much influence in SERPs - it's been widely abused by webmasters and Google has had enough of it's search engine being manipulated.