I don't see why either Nintendo or Sony would comment on Ballmer's claims; they're not privy to the inside information on whatever numbers MS posts.
Besides, announcing false numbers publicly would be more counterproductive than anything else. What? "Yes we we're #1 globally in 2011 based on our cooked numbers!"
Those numbers came from somewhere and I'm going to make a wild assumption that somewhere wasn't Ballmer's imagination.
Anyway, the shipping numbers should post more light on the subject once they're released.







