What really excites me the most about iOS 8 right now is Remote View Controllers, which I mentioned around iOS 6. Right now they are presented as something you use to implement services (extensions in iOS parlance), but combine them with auto-layout and adaptable view controllers, and you have a setup for presenting your app on an iWatch or an embedded display, for instance in a smart cover or an AppleTV widget. Embedding widgets accross iOS and mac devices is also an avenue I hope we developers soon get to explore. :-)