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I have a Tactile Pro keyboard. It has a power button, too. But like others have said, it only brings up the "Special" window where you can select Restart, Sleep, or Shutdown. When the machine is off, it won't turn it on.

I think the last time the keyboard power buttons still worked was on my B&W G3. Can't remember if it worked on my AGP G4...
 
The Mac needs to be in the right mood, a little soft music, subtle lights, and it helps if the keyboard is VERY sexy 😉
 
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