Have you seen this?
It looks pretty impressive

http://www.camcorderinfo.com/content/New-Back-Illuminated-CMOS-Sensor-from-Sony-Promises-More-Sensitivity-35234.htm#

picture seems a bit washed.
now they have to put the color filter at bottom too, because there is no reason to loose light in this filter, since you just need a bit of light to find how much of each color there is in each pixel.