An idea that has been discussed in forums for a while is now getting some development effort:http://www.rambus.com/us/technology/innovations/binary-pixel-imager/index.html
There is some connection to work of CMOS sensor inventor Eric Fossum, so it has some legitimacy.
On the other hand, RAMBUS seems to only take ideas to the stage of patenting, and then trying to license them to other companies for actual product development, making some people fear it as a patent troll.
Note that this is about improving highlight headroom at a given exposure level, not reducing noise. That is, reducing the base ISO speed of a sensor.
P.S. Sorry; I missed this related thread:http://www.luminous-landscape.com/forum/index.php?topic=75769.0