Eiji Aonuma says in the latest Edge magazine that the scale of the upcoming Wii release is what's foremost in his team's mind during development. Twilight Princess, he says, was the first Zelda game where they went for a more realistic feel in terms of size and scope of the world, and yet he feels that they weren't quite able to adapt all of their gameplay ideas to that larger space. As opposed to the DS-based Spirit Tracks, which Aonuma says started out in a much more traditional place, and thus was a little easier to "realize."
Aonuma says his team is starting out with a larger, grander world in the new Wii Zelda, and from there hopes to fill it up with all sorts of Zelda-esque game ideas. He and the team may not have been able to do everything they wanted with the adult Link-sized Hyrule the first time around (not that it wasn't well-received anyway), but they're planning to give it another hookshot in the next game.