Update: 10/08: xMatters for iOS 2.7.1 has provided a new workaround to this issue. Just launch the xMatters app once after upgrading to iOS 8 and you will automatically be re-registered for push notifications
iOS8 just hit the App Store and with it comes thousands of xMatters users upgrading to an entirely new smartphone operating system. A pretty amazing feat that Apple has accomplished, but unfortunately they haven't fully worked out all of the issues that go along with making such a major change to an important personal device.
In this case:
The iOS8 upgrade will require a user to manually launch xMatters for iOS v2.7.1 once to re-register their device with xMatters. Until this action is performed the user will not receive push notifications.
xMatters for iOS v2.7.1 is available now from the app store.