Nintendo caused quite a stir at the E3 gaming expo with its glasses-free Nintendo 3DS. In an interview with Japan's Sankei, Sony Computer Entertainment honcho Kaz Hirai had this to say about the glasses-free 3D tech:
In in-house research, naked eye 3D for portable machines is not high and there are presently limits for it.
Sony has always done this before with Nintendo, but usually later down the line they will release a PSP with 3D capabilities that doesn't have 3D glasses. I really don't think Nintendo has anything to worry about it, they already have their fans hooked on the 3DS, now they just need to sell it.