All documentation can be found either on our BukkitDev Page or our wiki here.
Although this video is a little out of date, it does do a good job showing off some of our features.
The latest GodPowers builds are available on our Build Server, here.
Keep in mind these are unapproved builds built from the latest source changes, so stability is not always guaranteed.
If you'd prefer to build GodPowers from source, clone the repo and, after installing Maven 3, use mvn clean package from the source directory to build the latest version of GodPowers.