Amos Posner at 2012-06-14 18:27:54:
I'm in the trenches with this right now. It's on an indie and I'm writer-director, but right now I'm editing my first feature, which is very music dependent. The two main characters are an indie radio DJ and a pop star.
In our script, we mentioned one big pop song that was important to the story. It's mentioned in the dialogue. It needs to be played. It's not just about tone or type of song. We needed to secure the rights before we shot or find something else.
One major indie band is mentioned, and we say a specific song of theirs is played in the script, but we were ready to be flexible if it had to be another song for money reasons. But again, this needed to be secured in advance.
In many other cases, we referred to the tone, genre, or volume of a song. Most scripts reflect tone and mood--ultimately that's what the music is for, too.
We had plenty of ideas for the rest of the music, but here's what's important: Unless you're the director, you don't know what the director's going to find fitting. If you *are* the director, you still might not know until you're in the editing room. And unless you're a music supervisor, you have no idea how the money factors in (a deep cut from the indie band cost more than the major, major pop hit). My writing partner is also serving as music supervisor, and even he has been surprised at some songs that have worked and some that haven't. Also, what if you talk about current music but the movie doesn't get made for five years?
All of which is to say, the most important thing in my eyes is blue printing. If a song is integral to the script, production *has to* secure it. If a song is perfect for the script, production *should* secure it. And if it's neither of those things, I'd say write around the specifics, while still conveying the mood (e.g. "They shout their conversation over ANGRY HARDCORE PUNK MUSIC blaring from the bar's speakers.")
Or to be more concise about my two cents--which are probably worth less than two cents--pick your battles. Mentioning one song is less likely to get you ignored than trying to curate the whole soundtrack on the page.