PostFerret is a back-end system for managing multi-user content generation and discussion. It is not intended to be a standalone application, but rather to provide a backbone of services to be used by applications such as LinkFerret and InstaGov.
I gather that this is very much how Drupal is set up at the data level (what I call a "post", they call a "node"), but it's not at all clear whether Drupal's API is set up to let me use it the way I want to use it. Given that plus the large learning-curve necessary in order to (a) figure this out, (b) learn how to interact with it, it still seems worth the time to "reinvent the wheel" rather than trying to figure out if I can use theirs.
If it turns out that Drupal would have been a good back end, perhaps PostFerret can later be rewritten as a wrapper around Drupal.