The thing is though, Nintendo is going through a completely different market than either Sony and Microsoft. That isn't to say that we shouldn't count them in the race, maybe in cumulative sales, but you can't directly compare them when they all target very different audiences. And when I think about it, the Wii is a pretty good compliment to one of the other two. Get a 360 and Wii, you're good. Get a PS3 and Wii, you're good. Hell, throw in a good gaming PC with either of those and you'r pretty much set.
If you want to compare their sales, sure, include the Wii, but you can't directly compare them when they target different demographics and different approaches to them.