Source Code
Download the Gnarus iPhone application source
Download Gnarly, the Gnarus server source
Keep a few things in mind: Gnarus requires an iPhone 3GS and an iPhone developer account. Also, the server web addresses are hard-coded into the source, these will need to be changed to point to your particular server.
See the included readme files for more setup instructions.
Future Development
The code linked above is frozen in time at March 2010. To follow future development of the code, check it out on GitHub.