Yeah, it indeed seems to be a standalone application with capabilities to convert, but no blender plugin. On the other hand though the latest version "Soya 0.14rc1" is from 01/20/2008, so not _that_ old or obsolete.
Soya 0.13 apparently can export blender2cal3d since 01/24/2007.
(I was about to include that info in my first post, but more than one "Forbidden"-forums' issues just made me cut text at some point)