I'll not be following it, but the afternoon phone-in might be entertaining. From Radio Scotland's schedule it looks more like a national Bill Drummond Day than a No Music Day.
Knowing what I do of Drummond I would guess this is as much about self promotion and ego as it is about a cause.
Still, I think it is a great idea. There really is too much music all of the time. And so much of what is easily accessible sounds like the taste of cardboard; case in point Matchbox Twenty.