The eminently sensible Dr. Bill Koslosky passes on the news that people with pacemakers and implantable defibrillators have nothing to fear from Wi-Fi networks: With hospitals increasingly deploying WLANs for mobile communications and data access, as well as less significantly for patient and visitor use, it's worth a worry. The good doctor notes that a session at the American Heart Association's annual meeting included results from German study--which had no commercial funding--which showed that even at the maximum signal output rates and closest distances, no "programming or telemetry functions" showed evidence of interference.
However, certain "noncritical pacemaker programming functions" could have problems at the highest output levels and closest positions--1 watt and 10 centimeter spacing. It's unlikely that one watt of power would be broadcast pointing at human beings from a distance closer than 10 to 50 feet, however, most likely being used in omnidirectional antennas located on roofs and streetlights! However, the recommendation was to not put Wi-Fi access points near outpatient pacemaker clinics, as a conservative recommendation.