According to Jedi Knote #5
posted on January 24th, former LucasArts composer and sound designer Clint Bajakian is editing the interactive music for Jedi Outcast. Mr. Bajakian, as you may know, has written music for such LucasArts games as Monkey Island 2, Indiana Jones and the Fate of Atlantis, Day of the Tentacle, Sam and Max, Outlaws, and Escape From Monkey Island. Clint has gone on to start his own company, CB Studios
doing freelance work for various companies. Here's a quote from the Jedi Knote:
Musically, Clint Bajakian (who produced music and sound for Star Wars: Dark Forces as well as many other Star Wars titles) has designed an interactive score, adapting John Williams' monumental film score to an interactive medium that dynamically responds to the player's situation.
So it doesn't sound like there will be much, if any, new music in this game. However, it is good to know that an expert on interactive music is on top of things.