I've received a tip that the new game Moshi Monsters Kastumi contains an exploit. It's highly possible, we've seen game save exploits in the past like cookhax on the DSi. Hopefully this will get released.
Edit, more info:
And to answer another question, the game is available in EU, US and JAp regions.
Edit, more info:
As Foxi4 has said; there are other games which are released which contain exploits, but are currently not available to the public. From what I gather, save files have to be powers of 2 in size, so like 512 Kb or whatever. Due to this, there is a portion of the save file which Is not used at all, and has no checksum attached to it. I'm unsure as to how the game somehow just jumps to this address. But I'm no hacker. We'll just have to wait and see.
And to answer another question, the game is available in EU, US and JAp regions.