
In its current version, it's not difficult to remove or disable, but on MacOS X, the fact that it's installed and running is not obvious to the user. On OS X, it can capture a snapshot from the iSight if equipped. This means that periodically, the iSight's LED comes on for a moment. This captured image is uploaded along with the location information.
One thing that males Adeona stick out from the competition (aside from its price tag) is that the location update information is securely stored on the OpenDHT network, a free, distributed hash table service. This means that no one can use Adeona or the data it generates to track you surreptitiously without having the retrieval file and the password you chose. Centralized commercial services often have the ability to track you, or their centralized information may become compromised. Adeona has no such risks.
You COULD potentially install Adeona on someone else's laptop, but if you're looking for software to help you spy on someone, there are a lot more efficient and feasible options out there. Adeona will get you an IP address and traceroute output. With the help of an ISP, this will help with a police investigation. If you have iSight photographs enabled, you might even get a clear photo of whomever is using your laptop to really seal the deal.
Once you install Adeona and select your password, a periodic schedule is started to gather and upload information to OpenDHT. It's that simple. Install and go. Whenever the laptop has Internet access, it will send periodic updates. You should copy the configuration file to a USB Key or have it backed up in a place that doesn't travel with the laptop, as this file is needed to get the location data from OpenDHT once you believe your laptop has been stolen.

Adeona will grind for a while, as locating and retrieving data from OpenDHT can take a while. Once it's done, though, you'll get a text file and optionally a graphic from the iSight camera. Here's my fugly mug and a pixelized Adeona status file (click to enlarge)
