And remember to turn off Bluetooth as well - the wifi and bluetooth MAC addresses are sequential - if you see one you know the other.
More paranoidly… A femtocell could fool your phone into revealing your phone number over the GSM/CDMA transmitter's channel. If I were involved in some extremely high value sale where the identity of potential purchasers was not always known, and where knowing it earlier might help close a sale (perhaps real estate or luxury cars?) - it'd be _so_ tempting to at least trial soemthing borderline-evil like that. (And now I'm inventing a small network of femtocells with directional antennas in white vans parked outside competitors - to track which of your potential customers are visiting which competitors…)
More paranoidly… A femtocell could fool your phone into revealing your phone number over the GSM/CDMA transmitter's channel. If I were involved in some extremely high value sale where the identity of potential purchasers was not always known, and where knowing it earlier might help close a sale (perhaps real estate or luxury cars?) - it'd be _so_ tempting to at least trial soemthing borderline-evil like that. (And now I'm inventing a small network of femtocells with directional antennas in white vans parked outside competitors - to track which of your potential customers are visiting which competitors…)