Wikimedia mobile language selection
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Fragment of a discussion from User talk:Hcatlin
I have a similar pending issue like this with chinese languages. They share the same wikipedia and have different language selectors. Currently, the mobile site doesn't really think about an interface language... but I'm definitely willing to figure out a way to make that work well.
I think you are right... more subdomains makes it easier.
If you wouldn't mind opening a Bugzilla ticket stating what you just said, I'd really appreciate it. It does appear that you can tell what their UserLanguage is via javascript:
wgUserLanguage="pt-br", wgContentLanguage="pt",