In the Fourth Open Hypermedia Systems workshop, the authors presented scenarios and a set of prototype tools to explore the application of open hypermedia principles, including content-based navigation, to temporal media. The purpose of the current paper is to provide an update on this work, focussing in particular on the ongoing work on content based navigation of music. We describe the development of a system which classifies the musical parts in MIDI files. This classification is then used to enhance content based retrieval and navigation of music. The effectiveness of the various approaches to classification is evaluated with respect to both stand-alone performance and when used in conjunction with a contour database.