Another nice set of pdf’s/slides about PBR for offline and realtime rendering.http://blog.selfshadow.com/publications/s2013-shading-course/ Brilliant information that is very relevant to blender, including an example of code implementations of the GGX and Beckmann-based specular BRDF’s (better than even the best implemented blinn phong PBR) for PBR realtime shaders. (now we just have to convert the hlsl to glsl). Also a nice little update post at http://mynameismjp.wordpress.com/2013/07/28/siggraph-follow-up/. Read everything on both these links, awesome stuff here.