I'm not sure if this is the latest version, but should point you in the right direction. My understanding is that pg keeps some aspects (eg, the hellbanning protocols) out of this code to prevent the system being hacked and overrun by spammers.
There are also other sites running versions (Markenomics.com comes to mind; News Mogul is no longer with us). Not sure how many of those have published their changes to source code.
I'm almost hesitant to recommend it though, because the service is terrible and they have not updated in months.
http://github.com/nex3/arc/blob/master/how-to-run-news
Question: What kind of server does one need to setup arc on it? Do you need like a total control (as in virtual/dedicated servers)?