A "Killer App" is by common definition one that is not available on other platforms and drives adoption of a particular platform so it can be used. If an app is

A "Killer App" is by common definition one that is not available on other platforms and drives adoption of a particular platform so it can be used. If an app is available on both iPhone and Android, it's not going to drive purchase decisions one way or the other in the way a Killer App would.