My understanding is that Sony spent a billion dollars developing this new three layered sensor. Each layer is sensitive to a different portion of the dynamic range of a scene. Those of you who remember the history of color photography know that there is a striking analogy here. The first three color motion picture process by Technicolor used a three strip film camera to capture the RGB color information. In 1935 Kodak invented something called integal tripack color film. It was named “Kodachrome”. The new film recorded RGB information on three layers coated onto the film base. Subsequent color films all used integral tripack to capture color information.
With Bayer sensors in digital cameras, RGB info is captured in one layer with some limitations on dynamic range. By devising a three layer, Bayer sensor Sony is increasing the ability of this sensor to capture a wider dynamic range. Eventually I predict that there will be larger sensors of this type for our DSLRs that will probably eliminate are at least reduce the need to shoot multiple exposures in HDR photography. Thanks Sony!