Yasuhiro Wada created the very first Harvest Moon before going on to work on Little King's Story and No More Heroes, among other games. So when Wada says he's developing a 3DS game, it's most definitely Good News.
Wada confirmed to Official Nintendo Magazine that he's currently working on a 3DS game, though wouldn't say anything more:
I've got a 3DS game in the pipeline right now, and I've got another game that we haven't decided the platform on, but which I am hoping to bring to Wii U.
Wada has previously spoken about his desire to release a new IP in the near future, so we're expecting something unexpected. As he's also chief operating officer of Grasshopper, we can't wait to see what Wada's team cooks up.