Zegnåt’s multi-level navigation. ‘Menu Master.’ (version 3., 20100519)

[yojoe]

Basing on simple ideas of other users, it's just a matter of nested pages.
Mostly top lvl pages are the language containers, and nested ones are pages in specific language.
It's mostly a matter of more than 2 lvls of menu and a chance to show defined siblings.

I think if your plugin would offer such possibility, then it will be the a menu+simplest language plugin in one

edit: forgot to add one important thing
If parent pages will be shown as flags (thus they won't be shown automatically in base menu) then there has to be a way to display a default nested pages.
It may be hardcoded ( to show childs the first parent) or used as a variable of menu() function.