Unicode is best known for its standards about characters. The CLDR is another project of the Unicode consortium, it provides key building blocks for software to support the world's languages. It is an extremely helpful resource and at Betawiki we use it more and more in our operations. One of the aspects of the CLDR is the translation of languages in other languages.
For many languages you will not find information in the CLDR. I blogged about a project for the inclusion of African languages before. There are also languages supported in the WMF that we do not have this information for. This makes it more difficult to support these languages in Betawiki and by inference it makes it more difficult to support these languages in MediaWiki.
I wrote to the nice people of the CLDR and expressed our need to include the names of our languages missing in the CLDR. They are willing to consider our special request. They pointed to their policy on what languages are currently supported.
The good news is that we can and will create a list for their approval. The better news is that their policy explicitly states that when someone wants to provide the minimal (level 30) information for their language, it will be accepted. For us as a community, it should be possible to do better then that. At OmegaWiki we have a list of languages with translations that should cover a lot of ground and we should be able to improve on this when we are permitted to include both the translations for other languages and the translations in other languages.
Please check out if your language is properly supported :)