Url please. I don't see it. The search on the blog doesn't return anything for ac3d.
Sorry Suezanne, I was posting from memory, which has once again proved faulty.
Anyway, the recent blog post "3 cool tools which solve common Second Life problems" mentioned "Avatar Databank with UV mapping info" which leads to this website;
http://www.ccccybernetics.com/avatar_databank/
That webpage mentioned "AC3D" and led me to this wedpage;
http://www.inivis.com/.
There I saw a link to "Second Life and AC3D: Now THREE great ways to build" which leads to these topics "Sculpted prim maker", "Box builder", and "Upload ANY polygon model in Second Life".
I only got as far as making a mental note to investigate AC3D further, as it appeared that it MAY have some potential for importing "outside" models into SL. Somewhere along that twisted trail was a list of several file formats that AC3D could import which is what caught my eye.