Upon request from several people I've re-done the high-ISO noise comparison between A500, A900, A700 and Dynax 7D. THis time I used artificial halogen light, a manual white balance (2800K), and manual exposure (1s, f5 at ISO 200, going down to 1/30s, f5 at ISO 6400).

The crops shown here are 100% crops from JPGs directly out of the camera.

ISO 6400:

ISO 3200:

ISO 1600:

ISO 200;