I recently stumbled up on the Adeona project, a free and open source system for helping recover lost or stolen laptops. You need to install a piece of software in your laptop and location information (in encrypted form) which is only accessible to the owner of the laptop, i.e. you, is sent to an OpenDHT node. (There are proprietary products such as LoJackForLaptops, PCPhoneHome, etc as well which do more or less the same thing, may be with different degree of privacy assuarnce)
Downloads are still not available but they have published some papers on this in some good conferences. My first concern is the privacy; I don't want others to keep tab of where I go! According to the researchers, their solution is privacy preserving. I also have some questions about its usefulness especially when the laptop's been stolen.
This solution works only if the laptop is connected to the Internet and the system is not modified or removed.
How hard it is to remove or stop the service running from the laptop?
How hard it is to spoof location information?
How do we quantify the level of privacy it provides?