Obtaining iTunes ID to an iPod player item

Question

I have an app that interacts with both the iPod player, and the iTunes Store Web Service Search API. Is there a way to obtain the iTunes ID for a song that I retrieve from my user's iPod library (e.g. via MPMusicPlayerController, or MPMediaItem)?

The documentation says that the MPMediaItemPropertyPersistentID is a unique identifier that persists across app launch. This however, seems like it might be a unique local id.

The only solution I can think of is to retrieve the song title and artist from MPMediaItem, then query iTunes to obtain the iTunes ID. Is the iTunes ID stored anywhere locally within the iPod library?

Thanks - I am pretty new to the media framework.