IGN has translated a section of the most recent Japanese Nintendo Dream magazine.
Most notable, the magazine said Nintendo currently has no plans to unveil the successor to the GameCube at the 2004 Electronic Entertainment Expo.
In software related news, GameCube sequels to Mario Tennis 64 and The Legend of Zelda: The Wind Waker are currently in development. Nintendo Japan is also currently preparing a release date for Wario World, which was released in North America in 2003.
The magazine also mentioned that a sequel to Animal Crossing is being considered. There has been no official announcement on the game's development however the staff is quoted as saying, "There's still a lot we want to do [with the game]."
Finally, according to the magazine, the Famicom Mini series of games released in Japan a week ago have sold enough for Nintendo to consider releasing additional games. Ten have been released so far and include titles such as Super Mario Bros., Excitebike, and Pac-Man. Nintendo has a large list of NES/Famicom titles to choose from if it decides to expand the Famicom Mini lineup.