The permissions stuff is tightly integrated into the android API, apps register everything they do with the OS as somewhat modular 'activities.' IIRC the permis

The permissions stuff is tightly integrated into the android API, apps register everything they do with the OS as somewhat modular 'activities.' IIRC the permissions are enforced at this low level, each registered activity has a list of things it can do associated with it and by adding all these things together you get the permissions profile that you see at app install-time. This Activities API is also what allows developers to so easily roundtrip to a third party app and back again from within their own app. The barcode scanner is a good example. EDIT: another example is how Launcher Pro lets you make homescreen shortcuts that "deep link" to functionality that is sometimes several menu-levels down inside an application.