According to Nintendo World Report, Nintendo will be ringing in the new year with a Super Mario Bros. 3 release in the Nintendo 3DS eShop on January 1st. The only downside is that it is currently a Japan-only release with no word on when it leave Japanese shores. It will sell for 500 yen.
It will feature download play for up to two players as well, although there are no specifics as to what this exactly means either. It most likely means that two players can play in the versus Mario Bros.-style mode, and not some new co-op mode, but that versus mode was fun back in the day.
And now we in the West will just have to wait and see when SMB3 will be available to us in the eShop.