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Most likely this is based on avalanche diode, used as an array.
Avalanche diodes (commercially available for two decades or more and widely used for detection of photons in variety of applications) behave like photomultiplier tubes: the photo- electron (expelled from crystal lattice when hit by photon) is accelerated in the strong electric field and on its way (when its energy levels becomes sufficiently high) can hit another electrons and transfers part of its energy to them.
The end result is couple of hundred of electrons created by the hit of one single photon. This amplification process does not add any thermal noise to original signal, hence it is useful for low level light detection and individual photon counting.
However, the device uses high voltages (100V), so I am afraid it will never be cheap.
Also, because such low noise is totally irrelevant for "normal" day-time photography, do not expect any sort of mass production of such devices.... If they appear on the market, they will remain in the area of professional applications.
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