Nikita Popov has posted a plea to developers and project maintainers alike to stop using XML for their configuration files in their PHP-based applications.
I recently tried using Phing (a PHP build system) to do some simple release automation. Just creating a PEAR package and doing a few string replacements here and there. The result? After several wasted hours I ended up using Phing only for PEAR packaging and doing everything else in a custom PHP build script. The reason? Phing uses XML files to configure what it should do during a build.
He advocates a more native solution - a PHP script that defines the configuration options as a part of an object that can be injected into the parts of your app without the need for external dependencies.