As of today, Level-5's Professor Layton spinoff, "Layton Brothers: Mystery Room," is available on the US App Store for iPhone, iPod, and iPad. I usually dislike spinoffs, but hey it's Professor Layton for crying out loud and it is made by Level-5.
The app is free, but part of the game does require purchasing. I think I read that total, the in-app purchases are about $5 which isn't bad. I hope this game is great.