You say controller light like it's some common thing. What does it even do?
It's for the PS Eye for motion controls. (The moves top = the light on the controller now)
It also displays battery charge and health in games as well as muzzle flash.
Killzone is using it as a health bar, when your health gets below I think they said 30%, it starts blinking red.
Nothing special or crazy, just mainly for the eye.
Watch the video your OP is showing in the pics, it's actually a cool video about the new features inside the DS4 not just the light but the new rumble pad features and other stuff. LINK
This post was edited on 7/9 at 3:11 am