Hi Tony.
It definately has an IR sensor. The power button is actually not a button but a smoked plastic lense over the IR sensor. The button is attached to the front panel PCB a little above the button itself and when pressed, it touches a microswitch just below the actual button. In between is the IR sensor. It looks a little like this (poor ANSI art following):
Case: ,______
|
|o anker
/ |
Button: ( |O| IR Sensor
\ |
|| <>| Microswitch
| |
| |
| |<-PCB
|
I just opened the receiver to verify that my initial guess was right, and it really was.
cu,
sven