Tim Cook just said during WWDC 2013 that multitasking in iOS has been revamped completely. iOS 7 will now monitor your app usage even more closely than before, meaning it will have apps like Facebook pull in news and other updates in the background, getting them all ready to roll when you launch the app. There's also a new panel for app controls called Control Center and a new look for UI when switching apps
The iPhone will now also adjust networking conditions to save battery life (so hopefully no more running out your battery while frantically trying to connect to WiFi), and there's a new notification management system that looks a lot cleaner and straightforward than the current implementation. These new features look terrific -- we'll get a look at them running in iOS 7 hopefully soon.
Apple iPhone 6s