A couple of scientists at the University of Washington managed to build a small scanner that could read the RFID signals that the Nike+iPod sports kit puts out. The range on these Nike devices are 60 feet, so it would be very easy for the right geeky person to track your every move. The scientists also linked their scanning system to Google maps for ultra-precise movement monitoring.
The point? If there is even the slightest chance that you may have a very geeky stalker, you may want to avoid running at night because these Nike + iPod kits are easily hackable, as it seems.
Nike+iPod raises RFID privacy concerns [News.com]