This is awesome! Are you able to implement the physically based specular term and still have acceptable performance?

You'll need the precomputed Beckmann distribution in a texture: http://developer.nvidia.com/node/171

Maybe. I didn't get yet to play with specular term, current one is just vanilla Phong.

There should be still some performance margin left, I tried to tune it to keep 60 fps on my notebook.

And it's done, if you clear cache and reload, it should be using physically based specular term.

Visual difference is quite subtle - skin feels more "silky" and ears are more shiny.

No noticeable degradation of performance.

Is there a review of the state of the art in skin rendering somewhere? Maybe I'm wrong, but wasn't it concluded several years ago that for realistic skin we would have no option but to use multi layer subsurface scattering? (honest question, I seem to remember that the last time I read about this around 2007-2008 the consensus had just about converged to that conclusion).