From my understanding PS wand doesn't have a IR ball. Also 2 points of reference can't tell you when you upside down yet it can tell you turning your wii remote. What Johnny was very careful not to show you was if he turn his head slightly toward to left or right of the screen it would zoom out and lean right or left instead of changing the view to the  right or left. That's because it only has two reference points so it can't track 6d movement.

 The reason you can be more accurate with movement the  IR points instead of the camera is exact like you can be more accurate putting a camcorder on a stand and turn the person in view around rather than keeping the person in video still and you walk around the person with the camcorder in hand.

 As far as tracking 6D movement the wand uses motion detection with the ball tracking. (that's the problem with wii-mote it's hard to use both motion detection and IR tracking at the same time since you got to aim with the wii-mote) Just how well this works we have to wait and see.

The giant glowy ball that's right on top of the Wand that is hard to miss >_>  that's an IR ball.

And with 2 points of reference you can tell when something is turning upside down...

You brought up one issue, the Wii remote does need to be pointed in the light sources general direction (about 45 degrees in any direction from the front of the remote) the ball also has the issue of something obstructing it's view if it be a person or you're turning it backwards, if the camera can't see it, it can't accurately tell where it is in that space just it'll just go by the general difference in movement much like the Wii remote.

As for the camcorder and the stand thing, that's a crock, its tracking movement, no matter which part of the set up of the setup is moving it's gonna track it as long as it's in range, so thats a pretty bad analogy.  The main differences you're going to get is that the person with the Wii remote can sit there and barely move their wrist to move the pointer, which works very well for FPS and TPS games, while the wand users could accurately have the controllers position mapped out in real time, that means while the pointer controls are looser you can do things like write your name and, dare I say it, have 1:1 sword fighting controls which would be better for things like Zelda and NMH. (note Wii Sports Resort has shown you can do it on Wii but you do have to point the Wii remote towards the screen from time to time)

On the other hand Nintendos solution is a bit more versitile, its funny you brought up some of the work Johnny did. While Sony basically needs the PS Eye to be the IR camera and the lightball on the remote to be the sensor, the Wii remote could just as easily be placed on top of the TV and Nintendo could sell a remote with Wii motion plus all added in except it also has a light sensor on top, therefore making it just like the PS wand with the exception that it had ports that you can expand the controller and actually get analog movement without having to hold a dual shock in one hand and a wand in the other.

 the work Johnny did was right off  the PC as even he noted. He just hooked up the wii-mote to his pc and use it as a camera just like pretty much any PC camera with a IR lens. He could have easily used a third light and copied right off from Track IR.
The reason why it's better to have a camcorder/camera on a stand is because any tiny movement of your hand equals a lot of movement in the distance. ( try to record something while you are running) A good camera like TrackIR can see any little movement with the IR points yet have a greater range and precision than moving the camera itself. Again this is why Johnny had the IR lights attached to his glasses and not the camera (wii-mote).

Correct me if I'm wrong but from what I've read Ps wand doesn't use IR lights but tracks four different color lights. (all the IR lights I've seen are directional as  with lazers) Since the PS eye will be program to track a certain color sphere it would be more accurate to track than someone's face which comes in many different shapes,colors and sizes. Plus if you use a IR camera lens, it filters out all light but IR light. (It also tries  filters out other IR sources like a stove or sunlight) So if PS wand use IR to track then it would seem to me the PS eye would have to have this filter which in turn couldn't track your face.