I was just installing a new X10 wall switch in my apartment, so I had the power turned off. I thought my computers might be on the same circuit so I shut them down first. After installing the switch, I turned the circuit back on. I tested out the switch itself, and it worked fine. Then I tried controlling it with the remote, which sends signals through the power lines. When I hit the buttons though, my computer turned on!!!
Wow, those ATX power supplies really scare me. :)
For those interested, the X10 code transmitted which seems to have been responsible for turning on my computer was "J 8 Dim"
I tried doing it again after the computer was booted, but it didn't turn off. That's at least comforting. :)