Nintendo apparently didn't want it, and now it seems that Sony passed on the Natal technology too, because it didn't think it did enough that was new.
With the PlayStation Move being so very much like the Wii remote, it's easy to forget that Sony has been looking into motion controls for some time now, first with the EyeToy, then with the Sixaxis controller, but the company didn't end up going down the path that Microsoft has with Natal and according to Sony's R&D Manager Dr. Richard Marks, it's because the technology didn't do the things that Sony wanted it to do:
"I love the 3D camera technology; personally, I like the technology part of it. We worked closely with our game teams at what it would enable, and it enabled making the things we already did with EyeToy more robust," said Marks.
"But it didn't really enable as many new experiences as what we were hoping it would enable, so it made the things we were already able to do a little bit more robust - which is good - but it adds a lot of cost and it didn't enable some of the other experiences we wanted to achieve."
Obviously Natal is yet to be released, so it's impossible to say whether Marks has a point about the technology, but from what we've seen so far, it's difficult to see what the Move can do that Natal can't; indeed, Natal currently looks like the more versatile piece of technology. Whether that is actually true, however, will have to wait until both devices are released.