Server Infrastructure Updates - Part 2: File System Sync

I needed a way to get the code base of the sites (Mostly Drupal 7, a few wordpress, and custom coded sites), upload images and other asorted media in sync between the two servers. I looked at the couple common utilities, I've used RSync in the past to maintain backups on other servers, but it has limitations on two way sync on multiple live servers. Enter Unison, it does exactly what the name implies, unifies multiple copies of the same set of files into 2 (or more) identical copies.