Paintball War Edition is a Bukkit plugin which adds fun snowball fights to Minecraft. 'Paintball Legacy' denotes the versions v1.+ of that project. Later versions (v2.+) are in the works, but not available yet.
You can download the plugin at its project page.
You can find documentation on how to setup and use Paintball in the wiki.
The wiki is a work-in-progress. In the meantime lots of documentation is still available on the project page as well.
For issues, suggestions or questions simply create an issue.