My daughter goes to a CoC school. Over the past year or so (on occasion) one of the students will bring a guitar into chapel to accompany the singing. I believe this is only happening at the secondary school where most of the teachers and even the principal are quite young and a somewhat progressive. This past spring they used a piano to accompany the chorus concert. I was a bit surprised. :)
[I spoke with my daughter today and found that what I typed above was not accurate. IM has NOT been used in chapel, but it has been used during spiritual emphasis days, which are held at another site.]
I really don't think they will introduce IM in the Sunday morning service any time soon. I get the impression that a few people might have to go to their eternal reward before that would happen. (I know... I'm bad. But how does one go about saying that nicely?)
Funny story: About 7 or 8 years ago, before I knew anything about the CoC and IM, there was a family at my church that had decided to get into a bit of "Christian children's ministry/entertainment". I recommended them to the school for a chapel service. One thing they did was put Bible verses to up-beat recorded music, and taught these to the kids. They also used skits and comedy to teach a Bible lesson. It's a long story, but let's say the staff at the school were a little shocked. My friends were not invited back there again! I didn't have a full comprehension about what happened that morning and how controversial it was until years later. :)