From Synet Electronics:
Laptop Anti-Theft works with any type of Internet connection including dial-up, cable modem, DSL, T1 and wireless. It recognizes and traces through both internal and external networks for LAN/WAN configurations to pin point actual location of the lost or stolen laptop. Once installed invisibly on your laptop system, Laptop Anti-Theft sends a stealth e-mail message containing it's exact location to a pre-determined e-mail address set by the owner. Each signal will contain all the required information on the status and physical location of your laptop. When the lost or stolen computer goes online it will send a stealth message to you containing information of its location using any Internet connection (Phone modem, Cable modem, DSL, ISDN, and Corporate LAN). Once this information is received, you can recover the lost or stolen property with help from law enforcement agency.