I was thinking that if Nintendo was smart they wouldn't just use WiiMusic as a simple game, but just as non-game game. Instead of simple conducting it should be a complete music suite. You could have the base mode which we saw at E3. Conduct your favorite songs and such. There could be new downloadable song from WC24 and the like. But then it could also include a full composition section (think Mario Paint). You could create a whole orchestrated piece in full written music, then conduct it! And you could upload the 'sheet' music and your conducting of it online! Then people could download new songs to conduct or watch/listen to songs other people have created! It would be a fun way for people to trade music, try their hand at making some, and for real music lovers it could be a unique way to be artistic and expressive.
WiiMusic could actually be a non-gamer killer app, and spawn a huge community of trading and creating. It would appeal to everyone, but also to the musical/artistic market. Like a MySpace of music!