Now with all three console platforms getting motion sensing, time to sum up some thoughts:
Nintendo's Motion Plus: Looks like a decent addition to the Wiimote, judging from the videos I have seen and the technical specs it won't do 1:1 mapping, but will give a much better detection of movements then the Wiimote alone due to the new gyro sensor. The best part about it is probally that sooner or later we might see Linux drivers for it.
Microsoft's Natal: It looks really impressive for the first five minutes, since its basically motion capture for use in your living room, but on closer inspection its much less impressive. Natal seems to only be able to track arm and leg movement, but not foot or finger movement, so it will be pretty useless for any serious gaming, as you don't have any detail in the motion data. Navigating a character or firing a weapon could get quite troubesome when the thing can't detect your hands properly. An additional controller would fix that, but so far Microsoft hasn't announced one. Considering that Microsoft hasn't shown a single demo that could be considered a normal full fledged game and it is hard to image how you would even do normal gameplay with it, Natal will probally stay a casual gaming device. It looks to much like a solution looking for a problem.
Sony's Motion Wand: Sony's solution looks to be by far the best of all. It doesn't do full body motion caputure like Natal, but it does full 1:1 mapping of position and rotation. Seeing the video where the controller was replaced by 3d objects looked really good and demonstrated how exact the tech is. Sony also managed to demostrage a wide varity of possible gameplay with the device (sword fighting, fps, rts, graffiti, etc.), so it should be quite useful for non-casual titles. As the device is finished its not yet clear how many buttons it will have and if it will feature an analogsticks, so they have still potential to screw it up. Another point that will be interesting to see is how good their pointing capabilites are, the Wiimote has a special IR camera and sensor bar for that, Sonys solution on the other side doesn't seem to have either of that, so it might end up less preciese in that area.