I think it hurts for the Wii, but helps for the 360 or PS3, many 360 gamers in their insecure 13-20 year old age would not buy an E-rated game... it would make them feel less... mature. That is why games like Kane and Lynch sell well on the 360.
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