There is no reason for that. It will be included I am shure. There are many languages that was not included but now they are. So, just be patient and until your language is not included you make web sites in other languages, like english.
According to Answers.com there are about 6900 known languages worldwide. If there are enough adsense ads for all the languages, the big G will surely display them. There are adsense ads in the Malay language spoken by millions in many countries, including Indonesia. So what is your problem? "Malay language, the language of Malaysia and Brunei, lingua franca of Samudera-Pasai (Malay Archipelago); Old Malay language(s), possible ancestor(s) of ..." - Wikipedia.org
Call up google and let them know you are ready to do business.. and maybe they will hook you up.. I think google is working on going total global more and more every day.. but can only deal with so many facets at a time. Hopefully soon they will work for you too.