With the way Google has been changing over the lst six month- it is pointless even to specylate about next PR update. I reckon even Matt Cutts is not sure about this answer.
I can only see this question so many times before it starts to really hack me off. maybe you will find a answer in one of the other 50 threads with the same title as yours. here is a head start - http://forums.digitalpoint.com/showthread.php?t=614571 http://forums.digitalpoint.com/showthread.php?t=616218 http://forums.digitalpoint.com/showthread.php?t=615510 http://forums.digitalpoint.com/showthread.php?t=615425 http://forums.digitalpoint.com/showthread.php?t=606981 http://forums.digitalpoint.com/showthread.php?t=612059 http://forums.digitalpoint.com/showthread.php?t=609956 http://forums.digitalpoint.com/showthread.php?t=601081 http://forums.digitalpoint.com/showthread.php?t=601048 http://forums.digitalpoint.com/showthread.php?t=598746 http://forums.digitalpoint.com/showthread.php?t=599205 http://forums.digitalpoint.com/showthread.php?t=591816 http://forums.digitalpoint.com/showthread.php?t=579828
Next PR update should be somewhere in March 2008. Following the trend in 2007, it is highly possible that we will face yet another stunning update in March 2008
March? Thanks God, I have time to optimize my sites. I think PR updates is in January, because after the October Mass pagedrop, google usually update it on three month (aprrox) which ins January.
if you want my opinion forget about pr it means didly squat as far as im concerned you dont need pr to get great results in serps unless you wanna sell links but hey thats against gods(google) rules