Man, so much has happened while I was gone (was hunting in the sticks. no internet). So from the look of things PS3 had a pretty big Black Friday just as I predicted. Although PS3 beating Wii for the month in the USA was genuinely shocking. Anyway, going by thismeintiel's thread:
http://gamrconnect.vgchartz.com/thread.php?id=135984&page=1
360 needs to outsell PS3 by an average of around 400k per week between the 11th and 24th. With FFXIII-2 releasing that seems pretty unlikely. I suppose it will be interesting to see how things play out.