iPhone developer adds “phone home” capability to stop app piracy.

"Ben [Chatelain] began thinking and decided to create a server callback system that would alert him when someone was running a cracked version of his application. The callback gave Ben information which included the UDID (Unique Device Identifier) of the iPhone. From there the server could then determine if the app was paid for or pirated. For those that were determined as pirated, the server would then allow the app to run as a demo and present the user with a message after 10 uses."