UPDATE: The DualShock 4's light can be turned off, Yoshida has clarified, but only at the developer's choice.
ORIGINAL STORY: There will be no way of turning off the DualShock 4's lightbar, Sony's president of Worldwide Studios Shuhei Yoshida has confirmed.
The vocal exec was quizzed on the matter over Twitter.
@DN_pro no— Shuhei Yoshida (@yosp) July 5, 2013
In addition to working in conjunction with the PS4's camera to determine the controller's position in 3D space, the lightbar can be used to enhance the game experience – an example is Killzone: Shadow Fall which uses the lightbar to display player health.
After initial scepticism, it turns out that the DualShock 4 is actually a great improvement over the DualShock 3.
There doesn't appear to be any major issue with not being able to turn the lightbar off, but some have raised the question of conserving battery life. There's also the suggestion that the light could reflect in TV screens, potentially obstructing the action.