When I was in high school, my math teacher would play Mozart during tests, claiming it would help us. It would drive me crazy, and I doubt that my grades improved as a result of the distraction.
For what it's worth, I have a BMus in Piano Performance. I love music... but never as "background noise"!
If it's something tedious, i.e. robotically making some kind of change throughout a code base, then my attention span can handle the additional load and the music may help me not procrastinate.
But for anything involving serious thinking, all forms of music I've tried are too much of a distraction.
I have ADD, which may be a factor.