PDNS-Admin maintains a subversion (SVN) repository for those who are interested in the "under the hood" details of what's being checked in and worked on.

There is a set of branches, which form the incremental releases, and a trunk which holds the "not always stable" code that's being worked on for more invasive changes. Typically it isn't necessary to mess with the branches as they almost never change, except for the most current.

The trunk is where most of the interesting work is done and is more likely to be of interest. Be warned though, it's not always going to be suitable for running in production and this isn't recommended. But if you'd like to take a stab, the trunk can be checked out anonymously from Google Code: https://code.google.com/p/pdnsadministrator/