The Music Ontology
Frédérick Giasson has published a first version of the Music Ontology Specification. The goal of this ontology specification is to provide main concepts and properties for music on the Semantic Web. The Music Ontology is expressed as an RDF/XML specification.
The current specification lists 19 classes such as Album, Artist, EP, Soundtrack, Track, Type and 50+ properties that apply to these classes. The classes and properties are based solely on the class, types and relationships defined by the MusicBrainz project.
Frederick has set up a Google mailing list for folks to provide comments and suggestions for the ontology.