Found this photoset by ttstam from the Flickr 5D Mark II – group. The noise control at high ISOs on the 5D Mark II looks impressive from these images. You really have to go to Flickr and look at the full resolution versions to see the noise performance. He also included reference shots with the 5D and 40D. (not the exact same shots though and they’ve been post-processed and HDR’ed)
Here is the shot at ISO 3200:
ISO 6400, slightly noisy:
ISO 12800:
ISO 25600, it starts to get noisy even in the downsampled version:
Fantastic sample thank you!