I had heard about that, that Sony already has the firmware to support custom soundtracks but that developers aren't using it. That is kindof annoying, when 360 users can just pull up their menu and chose a playlist on any game.
Well, it can be done two ways from a developer standpoint.
1) The XBox way where their base code must meet some standard to allow it to be accessed by the OS to turn off the game music and play the user supplied music.
2) The PS3/PC way where the developer optionally creates the game to access the HDD and allow the user to select his/her music.
Now each sway has its ups and downs.
1) Every user gets this option in every game. Great for the user from a customizable standpoint.
Developers have to work to a certain system whether from porting or whatever. But like it or not the devs are forced and I am sure that affects licensing. Why pay for in-game music at all?
And while by now it is probably not an issue I imagine that at one point in time it caused instability as the OS was basically hacking the game. No wonder Microsoft is the first to implement this standard.
2) Not every game has it so users are more often than not stuck with in-game music, which many times sucks.
Developers have a choice and so it may or may not be a hassle for them to include it. Not including it may help with licensing music.
This way is the most stable as it is an integral part of the game itself, not some hole allowing the OS to take over.
My big thing with customizable soundtracks is where it will leave the guys that have made careers writing music for video games.
Personally, I prefer original scores for games. Think about the music in Mario, Zelda, Halo, all the games with amazing original scores. If the industry gets some cheesy pop songs licensed for cheap and then gives us a customizable option what happens to the music that we associate with games?
So, I can live without customizable music, but only if you give me something that isn't mainstrem licensed music. If yo0u are just going to load me up with something like System of a Down or whatever then, yeah, give me customized.