I'm with Philly on this one. I don't really get the point outside of movies. When you see a band play live or a singing group they are in front of you. You won't typically hear random sounds coming from the left rear like an explosion in a DieHard movie.
For those who listen in 5.1 now, what's the difference with music? Is there a guitar panned back-right behind you for the entire song? I don't get it. Isn't that like standing in the center of a stage during a concert?