Is it possible to use the MoviePlayer and the MusicPlayer at the same time within an app?
This doc http://developer.apple.com/iphone/library/releasenotes/General/RN-iPhoneSDK-4_0/index.html implies it should not be a problem:
"In iOS 3.2 and later, the MPMoviePlayerController class now defaults to share the application's audio session for audio playback and related audio behaviors. This allows the movie player's audio to mix with the rest of the application's audio, as well as to conform to the behaviors of the application audio session's audio category (such as mixing with other applications' audio and/or obeying the Silent Switch)."