History of the Klingon Wikipedia
Decision to create 
The Klingon Wikipedia was created at a time when there was explosive growth in Wikipedias in the various languages of the world. Criteria for creation of new language editions of Wikipedia were then poorly defined and there was little process in place for determining which requests would be acted upon. This was also a time when other sister projects, such as Commons, Wikisource (then Project Sourceberg) and Wikinews were being established.
The existence of the Klingon project was divisive and led to entrenched debates over fairness and parity with other languages, and particularly with other constructed languages. There are several dozen constructed languages which have an equally strong case for the existence of a Wikipedia, depending on the criteria used.
Among the problems was the existence of interwiki links from the main page and other articles, which some Wikipedians felt detracted from the scholarly appearance of the project. Ultimately the interwiki links from other languages to Klingon were dropped, long before the Klingon Wikipedia was locked.
The project never attracted a community, in part because the fictional origin of the language means that there are no real-world speakers in existence who could form a community. Work was limited by the fact that the Klingon vocabulary is closed and incomplete, leaving no way to discuss many important topics without circumlocutions. There was ongoing discussion of the future of the project at meta, on mailing lists, and during board meetings.
In August 2005, Jimbo Wales made a decision to lock the Klingon Wiki permanently. While Jimbo has never publicly stated his exact rationale for closing the wiki, the maturation of Wikipedia and its sister projects as a whole into a vital worldwide resource meant that there was little incentive to keep a niche language that was not intended to be seriously used. Other constructed languages such as the Toki Pona language were closed at about the same time (although the Toki Pona Wikipedia, like the Klingon Wikipedia, was ultimately hosted at Wikia due to the presence of a strong community). At present, the constructed languages for which Wikipedias exist are Esperanto, Ido, Interlingua, Interlingue (Occidental), Lojban, Volapük and Novial. All of these have some speakers; the first three, and in particular Esperanto, have a community of speakers of notable size.