The Super Mario Bros. series has had a revival as of late, with games on the Nintendo DS and Nintendo Wii over the past few years. While Nintendo hasn't officially announced it, it appears reading between the lines in the latest Iwata Asks column that Nintendo is working on a game in the series for the upcoming Nintendo 3DS.
What follows is the conversation that references the game:
Miyamoto: Yes. So, in the interests of adopting new technology for the Super Mario Bros. tradition, I am now making a new Super Mario Bros. game for the Nintendo 3DS system.
Iwata: The next stage for the Super Mario Bros. Preservation Society's activities is the Nintendo 3DS.
Miyamoto: Yes. (laughs) I want to show everyone as soon as possible what the new Super Mario Bros. will be like on the Nintendo 3DS.
Given the Nintendo 3DS's 3D effects, New Super Mario Bros. 3DS should make for one interesting game indeed. Hopefully we'll find out more information about the game during E3 2011 later this year.
Source: Iwata Asks: Mario 25th