Updating this would be a nice project for anyone who's into reading source code or specs and being careful. (For example, is HTML allowed into the current music field on LJ? The RSS module ought to say one way or the other.)
Some prodding around on Google has revealed this is referenced in a book by O'Reilly so there's a decent amount of impact to be made for a small amount of work. I had started writing a version 2.0 but never finished it, so that'd be a good place to start.
(Note: I don't speak for SixApart, so maybe they already have someone working on this. I'll update this post if I hear either way.)