There is a major difference between the 3D Sony is doing and the 3D Nintendo is doing.
Sony: Supporting a new viewing format ala HD.
Nintendo: integrating a brand new display type (for places other than Japan) into their hardware.
If you still don't see the differences then I'll give you some more things to ponder.
- The 3D screen will be the central idea behind the 3DS, just as motion controls were behind the Wii
- PS3 3D support will be an added feature, just like the PlayStation Move isn't central to the PS3 experience, just an add on.
- Nintendo's 3DS will be the first mass produced consumer device to have an auto-stereoscopic display in the west.
- PS3 will join the computer at being able to support 3D screens and glasses.
Hopefully you can see the distinction here. Nintendo isn't copying Sony.
