I'm working on an open source tool for managing war files called warconfig. We have a need for this at work. I have a pretty detailed write up here. Warconfig is a tool for deploying, upgrading, and rolling back war files on Tomcat (currently only version 5.5 on Gentoo has been tested, though with a little love it should work on Windows and anywhere else that tomcat does. Support for additional app servers should be pretty easy to implement).
The coolest feature, (which is still in the process of being implemented), will allow one to easily see what has changed between war file versions. (Say you have a configuration file containing data specific to your deployment, such as jdbc connection parameters. This will allow you to quickly validate if you've updated your files).
Like the gentoo tools it was based on, it is written in python. This is a quick project and has been developed and tested in the past couple of days (unittests have made my life a lot easier, during various refactorings throughout the week).
So my question to you, lazy web, is what do you think of a tool like this? Is it useful? Overkill? Redundant? How do you manage configuration changes in your J2EE deployments? Please feel free to post your comments below.