Right now the BBC may be neglecting to use RSS enclosures for delivering audio and video content, but down in the digital culvert that is the BBC Radio and Music Interactive R&D team they are experimenting with annotatable audio - a system that allows the "collective creation of useful metadata and wikipedia-like content around radio programmes or speeches or podcasts or pieces of music."  Read more about this and see some screenshots of the demo here. This surely points the way to an era when all media is glossed in some way, either by 'individuals' (blog-style) or by collectives (wiki-style).