Famitsu just confirmed all the data-sharing options you could have hoped for in RPG Maker DS. What’s more, you can share data both locally and through online Wi-Fi.
First up is "card data," which is the term used for things like items and monsters. If you like a monster or an item in a game your friend created, you can obtain it via grabbing his card data. Then you have game data, which is the term used for sharing entire games. You can even send games locally to someone without a copy of RPG Maker DS through download play, but just like demos, they’ll lose the data once they turn their DS off.
RPG Maker DS releases in March 2010 for 5,460 yen. I doubt it’ll get localized but that doesn’t mean there isn’t an English-speaking community for the game.