I was reading a post on Kotaku about the new Wii 3.2 system software update, and I noticed that about 40% of the comments say something along the lines of "I haven't turned my Wii on since the last system update", or "I only play my 360 or PS3".
I have a 360, PS3 and Wii, and that is the order that I would rate them right now. The Wii is cool, and Wii Sports is the best game ever for when you have friends over. . . but I haven't really seen anything else that is impressive enough to hold the attention of anyone over the age of 25.
I know that they are selling many more Wii's than they are 360's or PS3's, but I bet 80% of them are collecting dust after the first couple of weeks. Microsoft has a crazy high attach rate, something like 8 games for every system sold. I'm guessing the Wii has about 2 games for every system sold. I hope that they come out with a killer app, or at least Wii Sports 2 in the near future.