Kojima implies music customization in MGS4

At Leipzig's Konami booth, Hideo Kojima made a little presentation and hinted at a couple of interesting things he's been tossing around in his mind for Metal Gear Solid 4. After the big trailer finally played (it had trouble the other day due to some technical errors), a rabid fan asked Kojima about the opening and closing tracks for the game. Kojima, not quite sure what the person was asking, shot out a tease answer anyway, "I almost slipped, but there might be a special feature where maybe you can play your own favorite tunes."

Now, we're about 85% sure that he meant an option to play all the tracks from the game would be unlockable, but he did say our own favorite tunes. Since Kojima has a lot of fun making his games, who's to say Snake won't come across an MP3 Player on his journey that just so happens to be full of your favorite songs? Snake can rock out while hiding in a barrel, we guess. What do you guys think? Misinterpretation, or a hint at things to come?