PHPBuilder.com has posted an article from Ian Gilfillan about one of the more popular PHP-based wikis out there, phpWiki.

This month it's time to look at another of those PHP applications I find useful on a daily basis. I like to use "wikis" for documentation for many of the projects I work on. [...] In this article we will look at PhpWiki, and we'll show you how to configure and use it with your own projects!

Ian includes a little history of the application along with the installation and configuration instructions to get you started. There's even a section there at the end talking about templates, wiki styles and links to other resources to get you up to speed.