I came across some wide angle lens tests for the Olympus OM-D E-M5 today and the same site also had tests of various lenses on the Sony NEX-7. First a health warning
: the results are expressed as "line pairs per picture height" and while the two sensor have essentially the same number of pixels in a vertical line (3376 for the Sony vs 3456 for the Olympus) the Sony obviously has pixels at the extreme left and right edges of the sensor which the Olympus lacks and that could drag down the NEX-7 average figures. That said the ""Max" figures should be directly comparable. It's also inevitable that the focal lengths have to be factored as, for the same field of view, a lens on the E-M5 has to have a focal length about three quarters that of a lens on the NEX-7 but even that figure is open to question as the aspect ratios of the two sensors differ.
With all that out of the way the E-M5 tests are here
and the NEX-7 tests are here
I'll leave interpretation and comment of those results to others but I thought I'd share here as it may help those wavering between Sony and m4/3rds models.