DocBook authoring and publishing support is available in easy-to-install-and-maintain packages for almost all widely used operating-system distributions:
CygwinPackages: for Microsoft Windows users
FinkPackages: for Darwin/Mac OS X users
DebianGnuLinuxPackages: for Debian GNU/Linux users
RpmPackages: for users on Red Hat, Mandrake, SuSE, Conectiva, PLD, Yellow Dog, ASPLinux, OpenPKG, etc.
XaePackage: for users on any operating system (includes integrated XSLT support)
TeiEmacsPackage: for Microsoft Windows users
EnovativeDocBookEnvironment: an easy-to-use, free DocBook environment for all Windows systems
DocBook Wiki