OK, I guess I need some help here... I'm one of those who really like the 'Fairy Tail' anime and buys the Blu-rays whenever possible. Has the original show finished airing or is 'Zero' simply a second series that's running besides 'Fairy Tail'?
Fairy tail is still airing, and the manga is still ongoing. Zero is a prequel, taking place before the main storyline. I've seen some popular mangas do it before (the only one i can recall right now is freezing zero). This is the first time i've heard of one of them getting an anime adaption though. Though it's apparently only got a single volume, and according to wikipedia it'll only have seven episodes or something.