Location based alarms

I found what may actually be a useful iPhone app - iComing. It's a location based alarm - when you arrive at a specific point (or within X distance of a specific point) it takes an action. Actions are one of nothing, poke Twitter, send an SMS, make a phone call, or ring a sound.

Uses:
* When I get within 5 miles of the train station, SMS my ride and tell them I'm here.
* When we arrive at the hotel, call my SO and tell them we arrived safely.
* When I get to my stop, wake me up

Location aware apps are the future - why is this only available on jailbroken phones? Why does apple cripple the iPhone (non-jailbroken apps can't run in the background, so location alarms only work if you do nothing else with the phone) and prevent the Glorious Future?