I have a site with 1600+ pages on Google's index. While the tool-bar PR shows only home-page PR and PR of a handful of inner-pages, I was pleasantly surprised when I checked it in my Google Webmaster Tools account. The information in my account shows that alll my indeed pages have Low PR (0-3). Another proof of tool-bar PR being irrelevant these days.
The toolbar is a useful rule of thumb but not nearly as accurate because it isn't updated as frequently. I use it all the time for checking PR, backlinks etc. it's useful and doesn't spam Google like some of the FF plug-ins
Sorry - but I must disagree that tool-bar PR is a rule of thumb. I never use a single FF plugins/add-ons as they are mere tools. Perhaps - it has been my mistake . The Screen-Shot is of December - 2008 and not 2009. PR updated on 31st December 2008. Perhaps you have guessed y bnow that - I follow PR of tool-bar and actual PR ( go to Google directory for it if your site is listed there) very religiously. If you have been doing it for nearly 3 years - like I've been doing - you would understand what I am saying. These days tool-bar PR means nothing -its all manipulated/hand edited/flagged-off result. Few months back - it was penalization with PR downgraded (pls read this post & this post to understand what I am saying). The second post is more important than the first one. But one can't understand the magnitude and importance of the second post before reading the first one. These days - tool-bar PR has become meaning-less, irrelevant and I believe in it after first hand experience of my sites. ( I never want my sites go beyond PR5 which I can easily achieved even these days of Google crack-down)