This site again provides a good example of what we want to accomplish - http://www.gettyimages.com/Music/search
- add tracks to a playlist(s) from the library
- rearrange tracks by dragging them up or down in the list.
- also add notes to each song
- rate songs based on your preferences.
- share your playlists via email with one or more colleagues or clients.
- package up and download the playlist as a single file
I've posted this issue in Drupal groups (http://groups.drupal.org/node/145189).