Google page rank is seen by some as an important measure for the quality of your website. However it’s seen as an on-going task to see the value increase. How much weight is put on it and should you get hung up on what it shows.
Matt Cutts explains page rank and how often it’s updated and how it can change and the reason why it changes. It talks about canonicalisation issues and content duplication. It also mentions that the reasons why the Page rank is not updated regular is to make web masters focus on quality content and good page titles to drive users to content.
If the Page rank was updated all the time then web masters would only focus on growing or maintaining the page rank measure and not generating the good quality content.
I suggest you look at the video and get Matts view.
