I started a new SourceForge Project called Doxsl. Doxsl is an XSLT 2.0 processing engine that generates documentation from your XSLT stylesheets, much like javadoc, .NET help, or Perl POD.
However, one of the more interesting features is the ability to generate documentation into DITA, HTML, and in the near future DocBook. This means you can create documentation for your stylesheets, integrate it into other documentation, or more simply leverage existing standards to output into any format those standards support (for example PDF and CHM).
You can find further details and download information at: http://doxsl.sourceforge.net