If you look at the images, they look very much like stacked planes. I'm guessing - and it's a guess - that there is some largely-transparent device which can generate light on points on a plane, and that it is being rapidly moved up and down like a piston head, creating a persistence of vision display much like LEDs on a bike wheel.

The low-light conditions the pictures are taken in support that I think - it might be that the "points on a plane" are some kind of florescent plastic and there's a scanning laser underneath drawing on it, so the amount of light being generated at any given point is probably very low.

Bear in mind that this technique can only produce light, not absorb it --- which means no hidden line removal, so it'll be good for wireframe images only, where you can see all sides of the shape at once. That doesn't mean it's not awesomely cool, but it's going to have limited applications.

IIRC, the piston-head technique has been tried before, and has always had the drawback that it's hellishly loud due to air displacement. I wonder how they're getting round this?

A vacuum?

Concerning the moving piston: Rather than have a moving plane, they could be using stacked, electrically-switchable films. Ones that you can switch from transparent to only translucent (i.e. scattering) very quickly. (http://en.wikipedia.org/wiki/Smart_glass)

We did consider that but smart glass is too far slow to turn on and off for it to work.

Yup, you've pretty much summed up the underlying principles of how it works, although we're not using a scanning laser.

It works for as many users as you can fit around it, from any angle, including above.

It's a electromechanical device, so getting it to holodeck size may be challenging.