I do not really want to keep publishing speculative articles on the website, when Sony has not seen fit (yet) to make any camera available to me but has apparently released models to journalists elsewhere in Europe a long way in advance.
However, reading what I've seen, and knowing what DxO actually do as a business other than making a raw converter and the test labs side, I'm willing to bet that what people are calling noise comparison and JPEG quality is actually neither.
Sony cameras to date have had 'IDC inside'. If you take a raw file and process it through IDC using the exact parameters embedded in the file by the camera, you will get a result which is virtually identical to the in-camera JPEG. It's harder to save the IDC result with the same JPEG compression as the camera, but the de-Bayer stage, NR stages, sharpening stages etc of IDC resemble the in-camera process so much that we can assume the cameras use 'IDC lite' internally.
Sony is now issuing DxO Elite as the conversion software with the new A500 and A550 (and also with the A850, but perhaps for different reasons). DxO also designs embedded processing for cameras. While the generation of BIONZ and firmware operating in the A850 appears to be unchanged from the A900 ('IDC lite') the look of the samples shown from the A500 just says 'DxO Optics Pro' all the way to me. If you took the D7D, A700 and A900 raw files instead of the in-camera JPEGs and put them through DxO Optics Pro Elite I know for sure they would look much closer to the A500 sample in every respect - colour, contrast, sharpness, noise.
We will, I am sure, be told in more detail but I think it will be found that the processing engine in the A500 and A500 has been provided by DxO. This may have contributed to the faster capture rate as well as the considerably higher final JPEG quality. Even if they had not changed their JPEG compression routine, the superior raw conversion would make the JPEGs appear far better.
So I think what you may get with the A500 and A550 is 'DxO Optics Pro Lite inside'.
The big question is whether Sony can retrospectively port this via a firmware upgrade to the A700 and A900 (or, indeed, to the A2/3 generations). It may involve areas of BIOS which are not updatable by the usual flashing method, or may even demand a new processor architecture, that they call it BIONZ still means very little.
If they can upgrade earlier models, why is the A850 not issued with this from the start? Probably because it does need a new processor board. The next generation A7xx and A9xx might well have just the same sensors as the existing models, but a new processor similar to the A500/550, and DxO Inside.
The good news is that I shoot raw, and DxO 5.3.3 - the new version specifically written for Sony - does an amazing job, transforming even ISO 6400 shots into virtually noise-free, highly detailed (if slightly artificial) final output. I think DxO 5.3.3 will be the subject of my next Photoclubalpha article, and any speculations (as in this post in the more private forum area!) will go into that as a subtext...