I'd just like to reiterate how utterly amazing MusicBrainz is. It's so extremely useful that I decided to make it the backbone of a new playlist format I developed[1], one which (roughly) uses MusicBrainz IDs instead of filenames for playlists.
This makes playlists resistant to filename changes, moves, or even losing all the actual audio tracks and having to buy them again, all because MusicBrainz provides so accurate metadata.