So how does it work? Prior to departure you set up an account with two sets of e-mails and messages. One for an OK, and one for a help. The OK can be used to track your location or the send an "I'm doing OK" message. The Help can be used to ask friends for help or to simply notify that you are in trouble. And if you are really in trouble you can hit the "911" button to call in a rescue. The google maps pinpointed locations from the previous post are from "Ok" messages sent with the SPOT device.
Though relatively inexpensive, there is a $99 annual subscription, and a $7.95 optional "rescue insurance". The first year of membership is paid for.
Though you all know, I still need to write this next part. Devices such as this one often time gives the user a false sense of security. One might place themselves in dangerous situation they otherwise might not because of the security gained by a PLB type device. A PLB is not a substitute for sound judgement, experience and preparation.