I've been using osTicket for my organization and evaluated it when it was eTicket.
An EXCELLENT open source package. Few come close to this. One thing I think will push this effort over the edge is an easier way to install (and possibly deinstall) modifications.
I currently use SVN to track the changes I make but it is still cumbersome to maintain and track.
My $0.02.....
I second this, we have about 10 mods and a fair few additional bug fixes in place in our installation, if/when we upgrade it will be a pain in the butt to move all across and also to ensure they will still work.
Upgrading could be a major problem for us because of it and potentially it could cost us more than time, e.g. additional staff hours
Rather then a patching system, I think that a module system (similar to Drupal's modules, or Wordpress's widgets) would be a fantastic addition. :)
