According to Nintendo Power, Epic Mickey for the 3DS will be a sequel to the Mega Drive classic game Castle of Illusion.
It will be called Epic Mickey: Power of Illusion and sounds like, basically, a platformer that will use the 3DS stylus to let players draw items into existence using Mickey's magical paintbrush. Drawing also plays a role in combat. The better you draw weapons, the better they work. But mess up a cannon and it could endanger you.
The levels are based on classic Disney cartoons, and even modern movies like Tangled will be represented.
Epic Mickey: Power of Illusion is being developed by Dreamrift, the studio behind under-appreciated DS platformer Henry Hatsworth in the Puzzling Adventure.
Note: The image above is from the original Disney Epic Mickey.