According to Natalie, the prequel manga episode of One Piece
will be animated. The DVD of the episode "zero" will not be commercially available, but 3,000 copies will be distributed to those who win a prize campaign in collaboration with House Foods.
(you have to purchase a special curry and apply for the prize.)
The manga episode will be published in Weekly Shonen Jump vol.53 to be released on November 30th.
Related news: Prequel Manga of One Piece To Be Distributed