According to a lengthy technical explanation posted a week or so ago on The Online Photographer blog, Sony has developed some new in-camera diffraction reduction software processing; that would be almost a necessity, due to the short flange to film distance (FFD) the new Sony uses. According to a Sony spokesman at last weeks big New York photo show, Sony also has some new data analysis and noise-reduction routines that are a first in the imaging industry. Combining those two imaging processes WOULD, to me, seem like a perfectly logical way to coax much better image quality out of the sensor.
We saw a similar thing with the Nikon D3x and the Sony Alpha A850 and A900, all of which used the same sensor; exactly HOW the image data is processed, and the quality of the electronics, is a big,big part of total image quality. In the D3x-A900-A850 trio, Nikon was able to get substantially better overall image quality out of the same sensor...the sensor that Sony had built and sold to Nikon for the D3x.
Combine a great sensor with high-grade lenses that are design-optimized for a new format (and NOT just adapted lens designs that might be 10,15,210 years old), and then add specialized software processing and specialized noise reducing software, and BOOM! VERY high image quality. I think there might howewver, be some image qualirty issues using OLDER, adapted lenses on the new Sony A7 series bodies, due to the short FFD.