Last night I was updating the man page for Bugs Everywhere to DocBook v5.0. I'm glad that DocBook is moving towards XML and processing tools I'm familiar with (xsltproc), because the SGML DocBook-to-man tools always felt a little rough around the edges.
If you are interested in DocBook-based manpages, take a look at my documentation and installation notes in the BE documentation. You can also try the official BE documentation, but that sometimes lags behind my version.