On the test wiki, I have created a special page to maintain interlanguage links. These are stored in a new database (wiki-intl). Please have a look at http://test.wikipedia.org/wiki/Special%3AIntl and try the examples.
This is an early attempt at best. What will follow (if all of you approve the basic concept :-) is a link from each article to the "add" and "zoom" pages (see link above). For example, clicking on "Link another language" (or something) will bring up the "add a link" page, with source title and language filled in.
Then, there should be an option to automagically generate missing language backlinks (probably on the "zoom" page).
I called the page "international issues" because I hope that it will later hold the interface translation strings, as well as the user database.
Magnus
P.S.: I posted this to wikitech-l rather than wikipedia-l, as it seems to be too technical and too alpha for the unwashed masses right now ;-)