According to 'Thorsten', who posted 8 development sketches by Milton Knight at Animation HQ (
http://animationhq.net/forums/index.php?act=ST&f=9&t=1030), Day Of the Dead was being developed as a feature by Warner Bros Feature Animation in 1995 but never got the greenlight. Though I cannot confirm this, it turns out that this project is now an animated short film nearing completion after a year delay: DMfx (
http://www.digitalmediafx.com/News2001/August/081901.html) commented in August 2001 that Day Of the Dead would be done via CGI, and follow the humorous day-to-day adventures of dead souls as they struggle to get through the Afterlife. You can keep an eye on the movie's progression via its official site (
http://www.dayoffthedead.com/index2.html).
So how's that for weird news, eh? I can tell you this now, it would kind of stuff up any originality in the Tierra story if it did come out! But it's caught me by surprise, it's the first I've heard of it.