Nintendo had considered releasing a 3D Gameboy Advance but put the idea on hold until the 3DS. The reason that they put the idea on hold was that the LCD screens back in 2001 didn’t have the quality needed to make good quality 3D screens. Also Iwata let slip that the Gamecube was 3D capable as well too but it would have increased production costs by quite a bit. He also mentioned that they did have a 3D version of Luigi’s Mansion as well. At least Nintendo held off on this technology until now, where 3D screens are readily available and are of a good enough quality to pass their quality control.
(via Slash Gear)