Yay there is a video on how the "PBR" setup was made. I am gonna try to merge it with this series of videos on more accurate PBR and hopefully get results good enough so that I can ditch the old already mentioned PBR build that I currently use: Changing HDRs and getting the right roughness might still be a painful though.
Unfortunately that's still pretty far off from PBR. The specularity isn't normalized and since there's no slot to change specular power on a material in the node editor there's really no good way to implement a roughness texture in the Blender viewport right now. It looks pretty decent, but I think it's a little…
GLSL PBR Shader for Blender's viewport is under development by this guy. And seems like he has provided a some sort of alpha or beta version to be used, not sure though: http://blenderartists.org/forum/showthread.php?343278-GLSL-PBR-Shader-for-viewport