I created a build script using Phing which has an XML based configure syntax (
build.properties), which is based on Apache Ant (Java).
It currently supports:
Installing WordPress and DB
Installing any plugins and themes from external urls (zip or gzip format)
Adding config details like site title, login name/pass, email (more can be added if your write php)
Adding custom detials to run or during install (must be written in php or phing syntax).
+ more stuff
It's not really a "config" file that you are probably looking for since it is run from the command line and requires phing to be installed and not directly read from WordPress, but it sure makes installing faster.
You can also have a look at :