Earlier quoted context omitted.
A real security hole, or one like "if someone watches you type your PIN code, they'll know your PIN code"?
Security holes that render the permissions system completely useless, since even a no-permissions app can end up doing anything.
The cases I've read about were of the form "app A asks app B to do something it can't via the Intent system". That sounds scary until you realize that a standard example of this is an app that can't access the network sharing something via email. In other words, app A has transferred control to app B and what the user does (or doesn't) decide to do with app B is their choice, not app A's.