Stanley Kubrick often mixed his films in mono(2001 being a noticable exception...), becuase he didn't trust theatres to have there sound setup correct. nothing worse than seeing an object move left to right and having the sound of it go right to left.
musics different and I really love the effect of stereo. but most of the posters are right, 90% of people wont hear the stereo mix properly. I work in a hifi store, and most of the people buying aren't setting up there hifi to get a good stereo image. most people today don't sit and listen to music, they listen to it as they do other things.
I like to record guitars with two mics, and pan them in the mix. the last track I did was a countryish number, and we used one mic on the guitar cab, and the other to mic the strings on the electric. panned one each way and voila, interesting effect.
Dr_Sbaitso