Most of these apps have two things in common; they will attempt to locate the whereabouts of the computer and also send a picture of the thief using the built-in iSight camera. Now a new name has appeared in the field; hidden. The name is apt, since there's no visible sign on the computer that the software has been installed. There's no app in the applications folder, and no preference pane. To use the application, you simply download and install it, then restart your Mac.
Most of the time, your Mac won't be sending out updates of its location. When it is stolen or lost, you go to the hiddenapp.com website, log in, and then change the status for the tracked computer from "not stolen" to "stolen." The service begins looking for your Mac, and within minutes the site displays a Google map showing its approximate location (determined through Wi-Fi geolocation) and, more importantly, photos of the person using the Mac and screenshots of what they are doing. Location updates happen every 10 minutes and also include traceroute information including the public IP address of the Wi-Fi network being used by the thief. This information can be provided to ISPs and local police to help you get your computer back.
hidden provides some helpful tips to get thieves to use the machine and not just wipe the hard disk. They recommend adding a firmware password to your Mac to prevent hard disk erasure, as well as setting up a guest account to encourage your friendly neighborhood burglar to use the Mac. It's also important to remember that this application won't work on Mac OS X versions earlier than 10.5, since the Skyhook Wireless SDK doesn't work on non-Leopard/Snow Leopard Macs.
hidden has plans for expanding the application in the future by adding key logging, remote wipe, and screen takeover functionality. Of course, none of these theft recovery apps work if the thief doesn't connect it to a network, and if they turn Wi-Fi off, there's no way to determine the location of the device. But it's unlikely, given the ubiquity of Wi-Fi worldwide and the desire for computer users to be connected to the rest of the world.
In practice, the hidden software worked just as well as some of the other theft recovery apps I've tried. The mapped location showed my computer within about three houses of my real location, and the IP address information would be usable by my ISP to pinpoint my street address. Even more damning evidence for a thief would have been the picture of his face and what he was using the Mac for.
Now the great news about the hidden app -- the service costs just $20 for the lifetime of your Mac. However, the company has created a special TUAW promo code that gives you coverage for the lifetime of your Mac for $10. Use the code TUAW50 to start protecting your favorite Mac for the cost of a couple of café mochas.
Check out a few screenshots below for an idea of how this app looks and works.