There was a feature on Once in this week's issue of Entertainment Weekly. In it, a few things were revealed...
-Kitsis and Horowitz do have plans for The Little Mermaid, but they're still working out how they're going to introduce Ariel, so they don't know if they'll get to it this season or the next.
-Peter Pan isn't public domain, so they won't be using him until the rights issues are worked out.
-[blackout]They say that the Queen is well aware that everyone is a fairy tale character, and we'll find out soon if the same can be said for Rumple.[/blackout]
-Whoever wrote the book that Henry now has is a key part of the story, and there are stories that didn't make it into the book because those involved might be considered villains.
-We might meet Henry's father and not know we met him.