Okay, I figured out the intltool magic, and the user viewable strings in the .inx files should be placed inside the .po files. I can't figure out how to make my Inkscape run in a different language, so I can't test to make sure that they show up translated. But, I believe that they do. The strings definitely show up in the .po files.
-- Translators --
If someone could go through their translation and make sure that all the GUI is translatable. I think this was the large set of strings that couldn't be translated. As far as I'm aware the entire interface should be translatable.
-- Extension Authors --
The inx files now support having an underscore in front of anything user viewable. So an attribute like "description" now also supports "_description". I've changed all the ones in CVS.
--Ted
PS - I'm really behind on the list, if you expected a reply from me on something, I hope I'll get to that today. Sorry.