That means iCloud won't be accessed except by applications that have been scrutinized by Apple, which cuts down on an avenue of attack by malware, and makes it

That means iCloud won't be accessed except by applications that have been scrutinized by Apple, which cuts down on an avenue of attack by malware, and makes it less likely that an application bug will cause problems with iCloud. The first thing that comes to mind with Notification Center is that perhaps it could be used for phishing-type attacks, by presenting a notification that appears to be from something else.