As of today, once an app is installed it will “look” for beacons even if your app is shut down or you’ve rebooted your phone.
We tested the functionality today to verify the new feature.
After opening an iBeacon app we hard closed it: not just putting it into the background tray but swiping it closed entirely. The phone still detected beacons and sent a message through the lock screen, something which in the past was reserved for apps that were at minimum running in the background tray.
The functionality even works if you reboot your device: after you power down your phone and start it up again, it will continue listening for beacons even if you don’t open up the app again.
The only concerns I’ve heard are battery impact and the ability to disable the notifications if they became an annoyance.
Given that this is Bluetooth LE, battery life should not be an issue. And you should be able to use Settings > Notification Center to tell a well behaved app to leave you be. [Via MacStories]