The Thai wikipedia now has an article on every district as well, the last weeks several Wikipedians started to create these articles, after many months of only an occasional new article. If I recall correctly the first such articles were created by myself in end of 2005, but only containing tables and other things which don't really need any knowledge in Thai language to create.
The last district article now created was on Phon Na Kaeo district in Sakon Nakhon. There are now only very few district articles left which haven't yet been converted into the standard basic outline with infobox, list of subdistricts, municipalities and TAO, and neighboring districts.
On the English Wikipedia a fellow Wikipedian and myself worked hard during last winter, and reached this state on April 9 2007. The first district article created by me there was on Chaiya back in February 2004, but I am not sure if that really was the first ever such article.