I downloaded raw data for three APS-C cameras with 12, 16 and 24 MP from Imaging Resource and measured resolution using Imatest.
The Imatest results were then plotted against sqrt(MP), which corresponds to linear resolution. The plots clearly show that we can make full use of the sensor resolution with the lenses used for the samples at Imaging Resource.
The data clearly indicates that present day DSLRs are limited by the sensor and not the lens. This also indicates that full frame DSLRs with around 50 MP would still make a lot of sense.
The measurements are close to the center lenses normally loose some sharpness near edges and corners.