If you didn't know what you were looking for, you'd probably miss it. It looks like nothing more than a keyboard cable that swallowed a roll of dimes. The company has an even more insidious version of the KeyGhost that is actually hidden inside an authentic Microsoft Natural keyboard. The brochure helpfully states that KeyGhost can be used as a backup to capture those really important documents that you absolutely can't afford to lose. The brochure also states that it shouldn't be used to engage in illegal activity.
Employers can use a packet sniffer on their LANs.
They may use keystroke monitors, too. In my state, Maryland, there is little to stop an employer from using them to monitor their employees. A security administrator would still have no idea what is going on at the workstation. KeyGhost excels at capturing data directly from a user as he or she types. Capturing keystrokes sounds like a foolproof method of surveillance.