Okay, the game's up. Thanks to James Isaac for doing the research.
As we can see, The Movie Center posted its 'quote' from Tim Burton about the Grim Fandango movie back on July 6th. A day later on July 7th, a detailed Wikipedia article created by somebody using the nickname "Wesborland" popped up. Take a look at this guy's contribution history and you'll see that he has been continually modifying the article ever since.
As you can see from reading through this thread, a user called Nick_Virago joined the Grim Fandango Discussion forums on July 9th asking whether or not anyone's heard anything about a Grim Fandango movie. A few posts later Nick claimed to have stumbled across this information on The Movie Center and Wikipedia:
Original comment by Nick_Virago
well, according to wikipedia and the movie center, the production of this movie was briefly announced, and there is no telling when the filming will begin:
The Movie Center
Take note of Nick's direct implication that he found the Wikipedia article.
Ever since, Nick has been posting links to all manner of obscure websites that 'back up' the original rumour, all of which reside on free hosting and/or reference The Movie Center as the source. Thing is, some of these sites haven't existed on the internet for more than a few days, and Entertainment Now hasn't even been discovered/crawled by Google at the time of writing.
Today on July 17th, someone called wes_borland left a comment over on the World of Monkey Island about the movie. Yes, the same guy who created the Wikipedia article a week and a half ago.
The best bit? I had a word with Dalixam over at the World of Monkey Island and it turns out that we've got an IP match between Nick_Virago and Wesborland/wes_borland. This guy has been directing us towards sites of his own creation while maintaining the act that he's been finding them.