... but you may need to download SL Viewer 7 from the SL website to see the change. Firestorm has also release v16.6 but it doesn't support PBR yet -- you can read about their roadmap here.
Actually I have been on SL Viewer 7 for some days now, and even though the CDS wasn't on the release channels that already supported PBR, I was already getting updates if loading an EEP environment, which have changed as well -- not that I am noticing any material difference on the appearance of the old ones.
So what do I see? Well, first of all, Gwyn's material-enabled leather jacket does look shiny now 
But I am also noticing changes in objects that have lights and particle systems, have a look:
On SLV7:
And on FS16.6:
Time of day moved between the two, of course, as I did a clean reinstall of FS which took some time. But you can spot the differences. Both pics have the CDS day-cycle, and ALS on with Sun+Moon+projector shadows.
I must say that FS16.6 never resolved those fairy lights, not even their twinkling script! At least on my machine, SLV7 is much quicker.
I am also noticing a change to objects with baked textures. This is my pavilion at the Amiais learning space, as seen on SLV7:
The vertical wooden posts should resemble better the ceiling beams, as all of them have the same PBR material baked in! But this should be easy to fix.
So I'll keep on SLV7, even though I do miss the really useful features of FS like Photo Tools, Inventory Collapse, etc. I have some thoughts about the interest of having two different teams doing two separate, incomplete viewers, but I don't have a lot of time to rant here:-D
