Just saw on the Vault wiki blog about a new feature they implemented: the "Media Location Controller", a system that not just loads certain music for certain locales like you could in FO3 (a welcome change from hardcoded like Oblivion), but also according to your faction status there.
http://fallout.wikia.com/wiki/User_blog:Ausir/The_Music_of_the_Mojave_Wasteland
If they revamped the music system that much, I eagerly await to see what more they changed.

They also are apparently remixing and revamping some older FO1/2 tunes as well.