"Killer app" usually means the app that motivates you to switch platforms. For PS3 or Xbox 360, it's the game that made you want to buy the console. For Windows

"Killer app" usually means the app that motivates you to switch platforms. For PS3 or Xbox 360, it's the game that made you want to buy the console. For Windows in the '90s, you needed MS Office to get your work done, so you bought a PC. All other things being equal -- i.e. assuming the system has a web browser and the other essential software has cross-platform equivalents -- the killer app is what kills off rival platforms. When I hear someone say "I wish I had an iPhone right now", it's usually because they're either (i) lost, or looking for something, and want access to Google Maps, or (ii) in the throes of gadget envy. The App Store addresses (ii), but not with any single app -- it's just the idea that there are thousands of fun toys that only iPhone users get to play with. So there are a couple of killer features, but nothing that can't be replicated on other phones. Not necessarily as well, but that's not the point: without exclusivity, the iPhone will not get the same kind of dominance Windows has.