The Apple Watch has what it calls a “taptic engine,” which alerts you to different digital notifications by silently tapping out one of several distinct patterns on your wrist.
I would imagine that with a little programming, one could combine the ability to speak into one Apple watch, like Dick Tracy, with the taptic engine output received by another Apple watch user. All of that could be done using devices that would not inherently be for illegal purposes. The programming could itself could also serve legitimate purpose. I imagine a legitimate app that provides such a function will likely be offered soon.
I saw that you already blogged about other ways smart watches could be used in casino cheating. I would imagine that offering those sorts of insight on applications of Apple watches to a mainstream media outlets could get some decent coverage at a time when Apple is in the midst of a big PR push for its watch. I might also indicate that you want to work with some programmers to develop such an app ... of course for legitimate purposes to allow discretely sending quiet messages.
As an aside, I wonder, but don't know, if the taptic engine could be used in reverse, where you could input information by a pattern of flexing your wrist, or whether it is only a data output method.