I'm guessing that the FAA have approved that it shuts itself down with pressure change or some such. You would need to get their name on it for carriers to accept it.
So it's on during the most critical phase of the flight, as prohibited for my iPad, by the same FAA. Such devices need to be signed off by other regulators and many airlines will want a look-see as well.
According to SITA over 99.9% of bags are reconnected with passengers and those that are irretrievably lost have no identification inside or out (or are stolen). I don't see somebody too lazy to put a copy of their eticket in their bag using something like this. (That will ensure any wayward bag is returned to you)
Even if they work, I don't see them as being that useful. So your bag is in Lagos, or Brussels, or in the dumpster at your origin and you're in Vancouver. Unless your airline has staff there I doubt this will expedite the process.