I wonder how they'd go about making the Address Book stuff require permission without breaking existing apps. They could insert a permission dialog, but there'd be no way for existing apps to handle the rejection gracefully as it would likely be a new method in a new SDK.

I guess they could just make all the "get" functions return empty data sets if the user doesn't agree for apps using the current functions.

They'll need to maintain backward compatibility to at minimum iOS 4, there's not many new apps that are iOS 5 only at the moment.