The raw data on sales numbers is all good but as soon as anyone can prove WiiFit sells more software than the PS3 then it will be something significant, but since there is absolutely no chance of that happening even if it outsells it 4-1, I'm sure Sony isn't losing any sleep over it..
As a game WiiFit is a beast and will never stop selling until it is the best selling of all time, but as a platform is not as significant...
PSN ID: T_Gears
End of 2009 ltd sales:
Wii = 67-68m
X360 = 38-39m
PS3 = 34-35m
Prediction: The PS3 will surpass the 360 on weekly sales after it drops to $299 on all regular weeks (no big releases).