An idea I had for describing composited audio such that copyrighted tracks can be resolved and an identical copyright conforming rendition can be created.

Resolvable Podcasting.xml

<?xml version="1.0" encoding="UTF-8"?>
<!-- Please read the blog entry for a description as to what this is: http://jphastings.tumblr.com/post/246130623 -->
<playlist simulatneous="true"> <!-- Or way informing that this playlist needs to be interpreted according to this article -->
  <chapters> <!-- A new element entirely. The Hospital Podcast is a good example of chapter use in Podcasts. -->
       <chapter> <!-- NB. There are other ways to define chapters -->
      <cueTime relativeTo="id_of_element">±3142</cueTime> <!-- Milliseconds in from beginning (+) or back from the end (-) of the track referenced -->
      <name>Name of Chapter</name>
      <image>http://path.to/image</image> <!-- Individual chapters might have the album art of the song etc -->
    </chapter>
  </chapters>
  <trackList id="MyPodcast" duck="true"> <!-- Auto-ducking can be turned off altogether -->
    <!-- Backing tracks can be 'ducked' while the podcaster is speaking -->
    <!-- NB. The player will duck track 'A' playing when a new track 'B' starts on top of it, unless 'duckable' is set to false for track 'A', when track 'B' is ducked instead. The same logic is applied for multi-track situations -->
    <track duckable="true" id="highway">
      <!-- These tags as per XSPF spec -->
      <title>I Am The Highway</title>
      <creator>Audioslave</creator>
      <duration>335000</duration> <!-- Duration is important for determining if the track desired is the same as the one resolved, but not required -->
      <identifier>MusicBrainz Identifier suggested</identifier> <!-- As the song is important, some way of making sure the right track is here would be a good idea -->
      <!-- Extended elements -->
      <cueTime relativeTo="MyPodcast">0</cueTime>
    </track>
    <track duckable="false"> <!-- This is a speech track, others should be ducked in preference -->
      <!-- These tags as per XSPF spec -->
      <title>Welcome note</title>
      <creator>Joe Podcaster</creator>
      <location>http://path.to/podcast_segment_1.mp3</location>
      <!-- Extended elements -->
      <cueTime relativeTo="highway">2000</cueTime> <!-- Start 2 seconds into 'I Am The Highway' -->
    </track>
  </trackList>
</playlist>