Uyghur is a Turkic language spoken by the Uyghur people in Xinjiang. According to the English Wikipedia, the language is written in the Arabic, Roman and again the Arabic script. Cyrillic is actively used as well.
The officials script in China for this language is Arabic and has been since 1983. The ug.wikipedia has a Latin script user interface. The ug.wiktionary however is right to left. This means that there is at least a need for a user interface that is either in Arab and one in the Latin script. Given that Cyrillic is another actively used script, we need three message files for Uyghur.
When a language is expressed in so many ways, the current MediaWiki software does not allow for supporting Uyghur in a meaningful way. It will be good when Multilingual MediaWiki becomes a reality. The good news is that the prospects for this are really good. The last status report I heard was that some install routines have to be written and then people can start experimenting with this new functionality.
PS Check out what MLMW offers :)