Let's see now...to make this technical approach work, the phone or other wireless device must:
a. Have an internal GPS or similar.
b. Have the local storage to store all the regions/zone definitions to which an alert applies. These must be stored whether or not the alert applies to the recipient because, you never know, that recipient may travel into the zone during the window of applicability.
c. Run an application locally on the phone which automatically checks its own position, then compares position to each stored alert zone. This must be done frequently, to see if the phone is in any alert zone during that alert's time window.
Put all these requirements together and you are talking about a wireless device with significant power requirements. Make your own call about whether this will "take the location market by storm."