It's also interesting to know whether or not DxO sensor ratings is something we should be guided by. If you compare new APS-C sensor ranks even with current full-frame sensors, new ones will have better performance: DxO Mark Sensors Comparison: Sony NEX-7, Nikon D7000, Canon 5D Mark II
Can someone explain me what's happening? Is this an improved technology used by all manufacturers (Nikon, Sony, Pentax) or some kind of hack (algorithms applied to RAW files in-camera) manufacturers use to make their images look better than they initially are?
call in moore's law -- advancements in miniturization and the design of IC's is boosting improvement each year. If you take the 5D classic and compare its output at 1600ISO, and put it next to a 60D at 1600... full frame does not always win.