This is processed using Photoshop ACR5.2 and the CS4 Distort>Lens Correction filter (really not a filter at all, but a major plug-in module). 5000K, 0 tint shift, +20 vibrance, 25L and 50C NR, 25 sharpening (to defaults), +0.5 exposure compensation, 25 Contrast, 50 Brightness, black point set to 2, Strong Contrast tone curve, Adobe Standard new camera profile, +50 R/C CA correction, +25 Vignetting correction; +4 barrel distortion removal in Lens Correction. Careful work on all the processing parameters in ACR to maintain natural WB while keeping blue sky noise to a minimum.
The noise prevalent in KM and Sony sky blues is also entirely down to red channel gain which is further boosted by Adobe Camera Raw's tendency to use too high a nomimal Kelvin value, and a magenta tint shift, for WB. Across the entire range from the D7D to the A900, reducing the Kelvin value below 5000 nearly always improves the result (and removing tint corrections of more than +5 magenta helps as well). The default ACR results from a typical Canon auto WB are equivalent to lowering KM/Sony WB by 500-1000K in daylight, but even in-camera JPEGs show a substantial warmth to the KM/Sony images. It is this warmth which is often making neutral greys and sky blues look more noisy than Canon images.