i think we can hope for beginning of january because:
1.) MWSF is beginning of january
2.) Intel releases Penryn Chips around that time and apple could use them in a MBP update.
but that is pure speculation of course. giving that this is 3 month away and actual shipping of the computers maybe a few weeks later and you probably don't want a rev. A product it is a good time to buy right now.