Okay, I'm too late to the party so my contributions are already prboably covered among these many posts. Still...
It's funny to see how the worm has turned. I see parallels here with E3'05, where MS showed what they had, and Sony showed what they hoped to have. this time, MS is showing a lot of hopeful lifestyle footage, while Sony are showing what they've got. The presenter really was nervous, wasn't he! He must have been practically crying during MS's conference! They pulled it back in the end though, showing a good case for the pro's of their system.
In summary, my appraisal is MS's system is by far the most elegant and intuitive, and the one people will take most readily to. Not sure when it'll be ready. I'm also not sure how it compares in some aspects. eg. Firing the bow, the camera could track the hands but if the release was occluded by the forward arm, the bow wouldn't fire. It also had quite a lag evident - not a game killer, but still a small barrier to immersion. The PS3 solution does look nerdy, but the tracking was instantaneous. They didn't show how much player motion they were following versus just tracking the widgets. The idea of buttons makes sense - theirs was a good argument about how you need a trigger to fire a gun. Nothing at all stopping MS releasing a versatile remote to work with their system though.
We need more examples of fine-control from Natal to compare motion performance. At the moment, what I've seen places the motion control advantage with PS3, intuitiveness with Natal. Also many of Natal's abilites shown are readily doable on other systems, but MS were the ones to show it and get the cred. Kudos to them! At least they're working on it and showing some benefits. Sony have had years to produce working systems and dared to release concept vids, but they delivered nothing. MS has given them a swift kick up the rear.
As for Nintendo, they're ahead with install base and reputation, but behind in technology. Which doesn't much matter, because they have a product to sell while everyone else is only dishing up promises!