Yann wrote:

I suppose that we want that the language changes acccording to users' settings with a "user_language" field in the user table.

A user pref to override the default UI language would be nice. Another thing that can be done in addition to that is have something like &lang=fr in the URL to force an interface change for anybody who has not set an override language in their UI (to French in this example).

I see a problem with the cached pages. We will need to have a cache for each language.

Language category tags (via the MediaWiki category system which is waiting for some more bug fixing before it is implemented) would be a way to solve that. Then when anons (who view cached pages by default) visit a page with a French language category tag in it their UI would switch to French (&lang=fr could then be added to history and talk page links so the French UI follows the anon).

-- Daniel Mayer (aka mav)