Ah, that makes sense. The only wireless keyboard I own is the one that came with my MacBook, so...
It's wireless in the sense that it's the keyboard for my laptop, which just happens to be "wireless" in one or more senses. :P
I guess since Apple computers nowadays don't really need to be turned on or off (typically, they come from the factory with settings to sleep them after inactivity) and since the "sleep" mode of a computer has been radically redefined over the last 10 years (used to be only hard drives spun down and the monitor blanked, now individual components sleep independently of each other, etc.), there really isn't a need for a power button on the keyboard -- control-option-command-eject does the same thing, basically (which I just found out by accident).