Interesting, but the simpler way is to use plain html with microformats [1], so this:

  @book{kn:gnus,
  AUTHOR = "Donald E. Knudson",
  TITLE = "1966 World Gnus Almanac",
  PUBLISHER = {Permafrost Press},
  ADDRESS = {Novosibirsk} }

  <div class="book" id="kn:gnus">
   <div class="author">Donald E. Knudson</div>
   <div class="title">1966 World Gnus Almanac</div>
   <div class="publisher">Permafrost Press</div>
   <div class="address">Novosibirsk</div>
  </div>

Impressive, this actually 'feels' like an extension for HTML (rather than some custom styles).