Yes, the light will stay on. This is due to an electronic component known as a capacitor. They are put into power supplies of almost all electronic devices, so that if the power dips, the capacitor will hold up the voltage. When you unplug it, the capacitor discharges whatever power it has left (if you were to pug it back in before the light went out, it would stay on steady, that's showing it at work). Although, you really don't have to worry about power with the Wii. In standby it only uses .5W (less than a typical night light). After time, you can also cause the pins to wear down from excessive plugging/unplugging.