No SMG is tracking ahead of NSMB world wide. While I agree that is pretty hot, one thing to consider is that NSMB was released in May, it did not see a holiday boost for over 6 month in NA at least.
End of 2009 Predictions (Set, January 1st 2009)
Wii- 72 million 3rd Year Peak, better slate of releases
360- 37 million Should trend down slightly after 3rd year peak
PS3- 29 million Sales should pick up next year, 3rd year peak and price cut