I guess they are different to normal sandboxed apps downloaded from the app store, since they have higher access to the iPhone (reading emails, controlling sett

I guess they are different to normal sandboxed apps downloaded from the app store, since they have higher access to the iPhone (reading emails, controlling settings), and can multitask (email, ipod). They may in fact not be apps at all, but just part of the system, with access via the icons. They are just made to look like apps. They may have hooks that mean they can never be deleted (like new mail), but only hidden, since there code is needed.