The PS Move looks like a carbon copy of the Wiimote except that is has enhanced reality function with the camera. PS fanboys are proclaiming that it is much more accurate than Wiimote, but I don't think it will have too much advantage over WM+, especially when it goes to translating controller movement into gameplay.

It just doesn't look original enough. By the looks of things, they are going to get a bunch of 3rd party shovelware games.
Natal, at least, is based on a more original concept.

Sony has never had much success at chasing Nintendo when Nintendo was the market leader. Their PSP has failed miserably at taking out the DS, even though the PSP has much more advanced technology.

Nintendo owns the casual market. Selling the Move in mid-generation is probably going to be too tough of a sell. Mid-console upgrades rarely sell well.

Nintendo will retain its edge through the end of this console generation. I wouldn't be surprised, though, if Nintendo tries to incorporate a camera as a future peripheral or into their next gen. They already have camera support in the DSi, so it isn't that much of a leap for Nintendo.

In conclusion, I think Move will do much better than the PS Eye did, but ultimately Move is still going to get squashed by the Wii. I still don't have any idea, however, of how Move will stack up against Natal. I will be watching this closely over the next year.