2
It is not a module - it is a hack.
It is not supported by the core team because it replaces core files. We (in the core development team) are trying to figure out a good way to implement multi-languages, but agree on the fact that Marcan's hack is - however well it is working - not a production-ready approach and will need to be refined before inclusion in the XOOPS core.
Can't give any timeline, though.
On a related note, I do use the ML hack myself, but I don't think I would on a site with a lot of changing content.