I'm keeping my fingers crossed that this little app will be as easy to use as it sounds. (Not familar with Ruby at all, but found that a Windows version exists.) There's plenty of .obj files here to test it on.
I'm sure blender is nice for people who know what they're doing, but your script sounds really great for those of us who barely tread water in that program. Loading blender is probably overkill for what we're doing, and I'm guessing that unless we know what to tweak - we're not doing it right anyways. (Thus the mats being all wonky, etc.)
Now if only there were someone who knew their way around Erlang and had an idea of how the .obj exporter worked and knew .ac... We could have a direct from Wings .ac exporter (importer?) plugin. ...But that's just me imagining things.
Then again... Maybe there's a Wings3D developer that might know enough about Ruby to translate the concept to Erlang... Hmmm.