Brian is going to be traveling to Italy with this young son and wants to be able to track him if he wanders off. Leo says there are gadget trackers - devices that are intended to be used for luggage, keys, etc. A key tracker on a necklace would be a good idea. Leo says there's a bluetooth device that sets off an alarm when his child is more than 30 feet away. What about using an iPod or iPhone and use find my iPhone? Find my iPhone isn't precise enough and doesn't work indoors.
Here's an article on Mashable of the eight gadgets and apps to track kids. He'll want something that has a locator, uses GPS and bluetooth, and raises an alarm when they break a set distance.