So I managed to find some time to look at the slow shutdown issue again, well at least a couple of minutes anyway. I created a new account on the mbp and started in that, making sure that none of my startup items from my present account were loading (I left the ones in the /library/preferencepanes on purpose. Sure enough it took a while to shutdown as well, which suggests that its a system wide issue as opposed to being limited to my user account.
During the weekend I also prepared and partition an external hdd ready to install leopard onto for further testing but I still want to see if I cant get to the bottom of this.
The thing thats been holding me back though is "Life on Mars", which is a BBC TV series, so far its been great and if Ive managed to find some time somewhere I have been watching that instead... bad bad but its definitely worth checking out if you havent done so already.
Maybe when I finish watching it I will finally sort this problem out? ;)