incrediBILL - 10:37 pm on Feb 23, 2010 (gmt 0)
Vista updated last night and the problem seems to have subsided.
Not sure it's fixed yet, but the run amok memory accumulation seems to be somewhat under control at the moment.
I have the machine loaded with a bunch of apps at the moment and memory utilization has been stable at 55% for a long time, before this it would just slowly climb for no reason.
Will report back when I'm sure if it's fixed or not.