A programmable power button could be utilized in a way similar to how the iPhone's volume buttons currently function as a shutter when taking photos with the Camera app.
As of now, the power button is only used for powering off the iPhone and putting it to sleep; it will be interesting to see what other uses are possible.
In the past, the iPhone's power button has always been located on the top of the device, but due to the larger size of the 4.7-inch and 5.5-inch iPhone 6, Kuo says the power button will be located on the side of the device. Like many of the larger Android phones out there, moving the power button from the top to the side of the phone would make it easier to reach when holding the phone in one hand.
Apple is expected to announce the 4.7-inch and 5.5-inch versions of the iPhone 6 at its Sept. 9 event, and will likely reveal its highly anticipated iWatch wearable, which is expected to be available early next year.
To get a sense of what the iPhone 6 will likely look like, you can check out this video of an iPhone 6 assembled using allegedly real parts and components.