Quote Originally Posted by Archangel View Post
As I understand it a soft on/off switch ramps the voltage/current up slowly, so as to reduce shock on components or in the case of a hand held power tool, it keeps the motor's torque from jerking the tool out of your hands.
Actually, it's typically used to debounce a switch so you get a smooth single on-off transition instead of multiple bounces from mechanical switches. However, in this case, it's being used to allow a push button contact such as those found on calculators and keypads to power on a PIC. The PIC then keeps itself on with software, until a software command is given to power off. The power off command could be given after detecting a second press of the power button.
If you follow the link to the original thread, in the first post in this thread, all is explained.