Here is the list of API changes to the iPhone SDK from 2.0 to 2.1. most of it is in the Audio Toolbox, but no iTunes/Library access additions.
AudioToolbox
- AudioConverter.h (Added entire header)
- AudioFile.h (Added 1 constant)
- AudioServices.h (Removed 2 constants, Added 11 constants, Updated 1 routine)
- ExtendedAudioFile.h (Added entire header)
AudioUnit
- AUComponent.h (Added one routine, Updated 1 routine)
- AudioUnitParameters.h (Added 10 routines, Updated 2 routines)
- AudioUnitProperties.h (Added 3 routines)
MediaPlayer
- MPVolumeView.h (Updated 1 routine)
UIKit
- UIViewController.h (Added 1 routine)