The following shaders implement physical and fast (non-physical) Sub-Surface Scattering in mental ray:
SSS_Fast_Material__mi : Material
SSS_Fast_Render_Shader__mi : textureMap
SSS_Fast_Skin_Material__mi : Material
SSS_Lambert_Gamma__mi : textureMap
SSS_Lightmap_Write__mi : textureMap
SSS_Physical_Material__mi : Material