Gump is Apache's continuous integration tool. It is written in python and fully supports Apache Ant, Apache Maven and other build tools. Gump is unique in that it builds and compiles software against the latest development versions of those projects. This allows gump to detect potentially incompatible changes to that software just a few hours after those changes are checked into the version control system. Notifications are sent to the project team as soon as such a change is detected, referencing more detailed reports available online.
You can set up and run Gump on your own machine and run it on your own projects, however it is currently most famous for building most of Apache's java-based projects and their dependencies (which constitutes several million lines of code split up into hundreds of projects). For this purpose, the gump project maintains its own dedicated server.
Apache dedicates a complete machine to running gump. The Build results page provides a view of the data gump generates for apache.
We're working on a new set of documentation. A lot of material is still available on our main website only. Also make sure to take a look at the wiki.