From IndustryGamers:

According to a new report from The NPD Group, console cross-ownership among Wii owners in the U.S. is fairly low. Wii owners, who represent 32 percent of all gamers, for the most part stick to Nintendo’s console. Only 14 percent of Wii owners also own a PS3, while 26 percent also own an Xbox 360.

In the meantime, PS3 and Xbox 360 owners are far more likely to purchase a Wii as a second console. How much of that is attributed to Nintendo Wii having such a broad customer base is unknown, but it is interesting information for those of us outlining a multiple console strategy.

Rather than just port the same game to all three consoles, special consideration should be taken to the audience the Nintendo Wii has built up, with credence to the top sellers for that system (namely Wii Sports Resort and Wii Play).  These are games that would not make it onto a hardcore machine, so why continue to try and push hardcore titles on this platform

More proof ?  How about Madden selling a paltry 67K copies on the Nintendo platform as opposed to 500K on the other two?  If you’re not considering the Wii and the 360/PS3 two separate audiences by now, you re doing it wrong.