I took two identical shots, one with the 7D and one with the T1i. Both with the 35mm lens at F2, ISO100, and 1/125. These were shot just a few seconds apart (the time it took to swap the lens over). These are 640x480 100% crops. The T1i fares well against the 7D, but the 7D had lighter exposure for the same shot. Just a pixel number or pixel pitch thing?
7D Crop
T1i Crop