I had an idea that sounded really cool to me.
This would correspond well with the wiki goals of Nabble, too.
Anyway, the idea is to have foreign language versions of all forums.
For instance,
http://www.nabble.it/Creative-Works-Forum-f15770.html would be just like the Creative Works Forum, only for Italian speakers (only without all the posts to the English one). True, this would result in a lot of blank forums to start with, but it would be rather convenient for multiple languages, and many people would probably be pleased (in the long run). Or, if you didn't want to get all the extra domains, you could do sub-folders as with
http://www.nabble.com/it/Creative-Works-Forum-f15770.htmlPosting in one language forum wouldn't post in another, but the forum structure would be the same (I would think descriptions should be the same, or blank, until they're updated with translations).
So, there could be a bar at the top with the language in it. Posts could be moved from one language forum to another.
Or, I guess you could make it optional, so when a certain language is needed a forum administrator can add it. That way there wouldn't be so many blank forums (although it wouldn't be so much like Wikipedia that way), and this would probably have to affect all parent and child forums (as well as, potentially, all cousin/sibling forums and such as are related).