ISO 12233 resolution chart test results have been added to the Canon EF 35mm f/2 IS USM Lens Review
The Canon EF 35mm f/2 IS USM Lens results are remarkably better than the results from the replaced Canon EF 35mm f/2 Lens
in the mid and peripheral (corner) areas of the image circle. Results in the center appear slightly better in the IS lens, but the differences are very slight - not surprising as the old lens was very sharp in the center.
Here is a Canon 35 IS vs. 35 non-IS comparison
(use the mouseover feature to see the differences).