SOPAC has a small but growing user base and developer community. In general, this site and the SOPAC project page on drupal.org should be your primary resource for help and support. There are several other options listed here as well.
If you are interested in evaluating SOPAC, Locum, or Insurge, a good place to start would be the Getting Started guide which will walk you through the installation and configuration of the various SOPAC components.
Several online forums are hosted here and may contain answers to many frequently asked questions. If you don't find and answer in there, feel free to post your question. Most forum queries are answered fairly quickly.
All official SOPAC documentation can be found in the documentation section of this site.
The SOPAC project page on drupal.org features a built-in issue tracker. If you feel you have found a bug or would like to make a feature request, that would be the place to do it.
Oregon-based CraftySpace currently implements and supports SOPAC through their YourLibrarySite.com service.
BibLibre, a French company, is also involved with SOPAC. They are familiar with the implementation and operation of SOPAC.