Degausser on 23 July 2011
I think the main reason is that Microsoft will always put everything behind one 'big' exclusive for the holiday period - Halo Reach last year and GoW3 this year etc. This means Halo / GoW rack up 'big' sales as the big holiday game, whereas Sony spread their sales a bit more (Resistance, R&C, Uncharted and Twisted metal all coming this holiday... albeit with a clear 'focus' on Uncharted).
And the other reason is there are more 360's out there then PS3's... further emphasized when you consider a chunk of those PS3 sales are Japan too - which sells very different software... making it harder for 'big' numbers as it's hard to get sales from the east and west.
