According to Cult of Mac, this new feature is available to third party developers and Camera+ is the first third-party iOS app to incorporate it.
With this new low-light boost mode the maximum ISO is increased from 800 to 3200, a two-stop boost (stops are the doubling of the ISO).
A little extra noise is added to the photo but this allows you to take better pictures in low-light conditions.
The sample images from the Camera+ release show the difference between the iPhone 4S and the iPhone 5′s camera.
Camera+ can be purchased from the App Store for $0.99 and the update is now available in the iTunes App Store.