Peter Huboi gave a few ideas on how wave can be used for music industry. http://marketingplaylistpower.wordpress.com/2009/06/15/how-will-google-wave-impact-online-music/
Paul Böhm talks about what wave is. The important point, as he points out, is that wave's potential goes wells beyond the current wave UI. Evaluating wave based on current UI is selling short of its potential.