CoeLux: Artificial Sunlight That's Real Enough to Trick Your Camera and Brain

Sadly they write little substantial about the internal construction principle so I'm making an educated guess:

Based on the pictures one can see that relatively hard shadows are created as expected by a point-like light source (like a far away sun). Also in the movie it can be seen that the 'sun' moves with the camera when the camera moves.

The hard shadows would be created if all light emitting the 'window' are almost parallel, which would require some kind of optics. So I'm guessing that the 'skylight' is made of a slightly curved backside supporting a large number of white LEDs. Each LED then would have a small lense so that all light is emitted within a very narrow angle. The slight curvature of the backside would then lead to the apparent movement of the light-source if the camera moves. (Because one would look into the opening angle of a different portion of the LEDs)

The blue color itself is a layer of nano-particles leading imitating Rayleigh scattering of the atmosphere.

More info in this June 2014 article: http://www.gizmag.com/coelux-skylight/32469/

Very nice but I have a feeling that this will have mid 4 figures price tag attached to it if not higher.