LensRentals' Roger Cicala has published an interesting article comparing 24-70mm F2.8 lenses from Canon, Nikon and Tamron, using both an optical test bench and Imatest results from Canon EOS 5D Mark III and Nikon D800E bodies. This provides some insights about the interaction between the sharpness of the lens and resolution of the camera's sensor, and under what practical circumstances you might see any difference.

It's worth reading for anyone interested in the long-running question: what provides more detail, a higher resolution sensor with a good lens, or a lower resolution sensor with a great lens?