In an interview with Nintendo president Satoru Iwata, the man behind the development of the Nintendo 3DS said a version of its 3D technology was being tested as far back as the company's GameCube days.
Hideki Konno told Iwata that Nintendo developers had tested 3D technology with Luigi's Mansion shortly after that game was released. By Konno's description, it sounds like they were working with a peripheral or a separate device to provide the 3D experience with the GameCube game.
"The reason we didn't move forward was at the time the console and the 3D device were separate," Konno said. "And it's not playable unless have both. Now it's all in one (with the 3DS), including the LCD screen."
Iwata noted that Nintendo had also tested a 3D version of Wii Sports golf soon after it was released.
"When you hear 3D, people think of characters coming out of the screen," Konno said. "But after you started, the sense of scale became much clearer on the screen, and it's easier to gauge with your eyes."
The full video interview is at e3.nintendo.com