It’s common currency in some technical communication circles to deride DocBook as being dead. If not dead, then gasping its last. But documents authored with DocBook do turn up in a number of unexpected, and expected, places. Places like the documentation for free and Open Source projects. And even at a commercial publisher or two. Like who? Like O’Reilly Media. O’Reilly, according to the DocBook wiki, has “a pure-DocBook workflow for books (from author manuscript to the printer PDFs)”.
This guide (when prompted, enter guest as the user name and leave the password blank) discusses how to get started writing with DocBook. Admittedly, the guide is aimed at authors working on books for O’Reilly, but you can probably learn something from the sections on using Subversion and working with XXE (a popular XML editor).
If nothing else, this guide is an interesting look at an XML-based writing and publishing workflow.