interview with LevelUp, Nintendo's Miyamoto hints that we might be seeing the Miis marching out of their parades and into virtual worlds similar to The Sims. Since Miyamoto didn't reveal much at GDC this year (in part due to shareholder regulations), they grilled him about his speech, and about Sony's PlayStation Home announcement.
While Miyamoto claims not to have seen the video of Sony's goods (which is hard to believe, you think he'd be studying up on the competition) he does go on to say, "I wouldn't be surprised if we also did something along those lines further in the future ... in terms of taking the Miis and expanding them, that virtual kind of Sim-type experience. It's something that a lot of people have already done and shown interest in, and we have a lot of people internally who are interested in that type of a project too."
We'd be interested too, as long as it doesn't feel like Nintendo is trying to copy anyone else's effort. Bring on something that allows us to take our Miis out of the house using the DS. Maybe you can teach them new skillz in some kind of game, and then bring them back home, or take them to visit someone else. Then they teach that person something new, and they teach two people, and they teach two people and then the world is taken over by Miis.
Check out the full article for the details, as well as Miyamoto's description of bizarre-sounding game called Love and Berry.