Padraic Brady has posted part one in a new series he's developed covering documentation (and using Docbook, Phing and Apache FOP to create some professional looking results).
This article series proposes using Docbook XML as the ultimate source format for all documentation. The difference between most formats and Docbook, is that Docbook can be used to generate numerous final formats. [...] The series was written to introduce programmers to a PHP oriented publishing process which uses Docbook XML as the basis for generating professional looking HTML and PDF output.
Part one introduces the "ingredients" - Docbook XML, PHP5, Phing and Apache FOP - and includes an install process to help you get things set up.