Dunno how closely it tracks the version that's actually on the site, I think it was forked from PG's release a while back and various people have patched it.
Here's a brief explanation of how to get it up and running - https://github.com/nex3/arc/blob/master/how-to-run-news
I had arc.news up and running a few months ago. The code is quite outdated but has all the essentials to get your own HN site. Truthfully, it'd be very nice so get a crack at some more recent code.
Personally, I'd love to use arc.news to run a closed news aggregator/discussion site for a close group of friends.