translatewiki.net there is a page with MediaWiki extensions with localisations in more then 50 languages. It was not updated for some 15 months and now it shows 314 MediaWiki extensions up from 128.
The Babel extension for instance supports 186 languages and, it is an extension that several Wikipedias requested to have installed.
The Wikia extensions only recently found their way to translatewiki.net and, there are already some who have localisations in over 50 languages..
All this is possible thanks to our wonderful community, you can always check out how your language is doing; we can use help in localising, proof reading and helping us maintain and develop our project.