Turn Off AirPort and BlueTooth?

If all you are really worried about is security, turning the wireless off via System Preferences definitely turns the transmitter off, not just access to it. I've confirmed this myself, and not just from Mac to Mac (where in theory Apple could just have each machine say 'pssst, I'm turned off, I'm not here'). Windows and NetStumbler couldn't see the mini, neither could any utility in Linux. When you turn off the transmitter, it's off. If you are really worried about the WiFi and never wish to use it, you could certainly open the unit and unplug it. If you are really never going to use it, you could remove the whole unit (depending on model) and sell it as spare parts.