SonyAlphaRumors says it got this rumor from the known source:
"Sony is currently prototypeing Image Sensors based on SiOnyx or better known as “black silicon”. Basically it uses a porous silicon etch on the front side to reduce reflectance. However, while this works well in reducing the visible light reflectance of bare silicon wafers with no backside layers or materials from 46 % to a few %. For image sensors a sensitivity invrease of 30% is estimated."