@Alby:
1) Sony's move controller is exactly what Christensen means with least effective + bad execution! The Move controller IS a direct copy of the Wii remote. It has the main unit, almost the same buttons, a nunchuk, the pointer, everything. That's like saying Microsoft didn't copy Apple when it came to user interface because their computer mouse features right-click! It IS a direct copy. If Sony had added something new, something that would enhance on the whole concept you'd have a point. But this is exactly what Christensen meant with copying. He is looking at this from a consumer point of view. To 99% of the consumers Move will look exactly like the Wii remote. Imagine someone inventing a new type of car and someone else copies it, paints it black and puts the engine at a different place and then says "no we didn't copy! Look it has the engine on the left side! And we added this thing nobody needs!"
To die-hard gamers like us there might be a difference but to the average consumer there isn't. My TV remote also has a different button shape than yours but both are the same. Oh and adding that color-ball doesn't change this 
Also, when Christensen says "bad execution" he means that the incumbant didn't understand the values of the disruptor which again is exactly what happens here. Sony thinks people will "upgrade" to the PS3 motion because it is "better". They don't understand what makes the product "better" to consumers so this is exactly what Christensen calls a bad execution.
Oh and Natal is not disruptive! Nintendo is disruptive but Microsoft is only trying to counter-act this so this is not a disruption. Natal would be disruptive if it offered something completely new, with a different business model, etc. But Microsoft is only adapting to Nintendo's rules.
2) Even if it is only 30$ that doesn't matter. What makes the Wii "good" for consumers is the software. The only thing Move will offer will be clones of Wii games (why should people "update" to play the same games? That doesn't make any sense) and a number of crazy gaming ideas only a fraction of the consumers even care about. That's what always happens when you add something to your console after 3 years. So consumers can either go for the Wii which was built upon motion controls and features dozens of good games or for the PS3 which features a fraction of the games but "in HD" (which doesn't matter at all).
3) True we can't know. But so far it looks like Sony still doesn't understand why people like the Wii (they think people will "upgrade" because of HD! That's enough proof, isn't it?
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