Compared to...

Studio scene comparison (higher sensitivity)

As we observed in our ISO sensitivity / Noise levels test the 7D appears to use noise reduction and sharpening reduction to maintain low noise levels at higher sensitivities. This can be seen in the crop below, the 7D image looking quite a bit softer and exhibiting less detail than the D70. The difference compared to the EOS 20D is more obvious, Canon's CMOS sensor working well even at high sensitivity with very little difference in detail even compared to its ISO 100 performance.

Konica Minolta 7D, ISO 800
Nikon D70, ISO 800
Canon EOS 20D, ISO 800