Cellphones in the USA seem not to cause a problem. My UK one plays havoc with the VOR and ILS in the Arrer if I forget and leave it on. Something to do with GSM compared with the PCS (or whatever it is) system.
My laptop and my pocket PC have Bluetooth, but it can be turned off. I've not come across any device with "always-on" bluetooth. The WiFi card in my laptop is PCMCIA rather than built-in, so I don't know if built-in ones can be disabled - but presumably they listen before they transmit anyway?