I've been fiddling around for ages and I think I've finally come up with a skin fix system that actually looks pretty natural. I'd appreciate your views as to whether you think it looks natural or not...
Roughly, it's done in CS3 with a high pass filter switched to vivid light blending and the "blend if gray" sliders are adjusted until you regain some highlights. After that, it's all inverted and a layer mask added so you can paint the smoothing in where you want it. I've also added some texture back in with another, but very gentle, high pass filter and some noise with that layer switched to soft light blending.
Looks like this... (original on the left obviously!) - Click to embiggen
