Guy English, spelling out what Apple's Push Notifications already do and how they relate to iCloud:
The “Push Notification” persistent connection enables:
Push Notifications. In badge, sound and text flavours.
Find My iPhone. Asks the device for its position and provides for sending a message, locking or remote wiping a device.
FaceTime calls. Works with iPhones, iPods (let’s drop the ‘touch’, iPod Classic is dead) and iPads. Oh, and now Macs.
iBooks bookmark syncing. Transparent and works across all iOS devices.
Enterprise Wireless Configuration. iOS provides a mechanism through which enterprise customers can remotely reconfigure the devices they have in the field. It’s all very boring until you think about how that might work.
So there’s a fair amount of functionality we take for granted in iOS devices that’s already being provided over this one persistent connection. Not all of these features are likely to run entirely over the persistent push connection, but it is the control line that kicks things into action. iOS 5, and the set of services branded as iCloud, seem set to blow this pipeline wide open.
And then Tim Ricchuiti, hitting the nail on the head:
It’s kind of funny, actually. I can’t say whether Apple planned it this way, but the push notification system should be regarded as a failure if it’s purpose was simply for notification. Apple’s implementation of the more Android-style notifications in iOS 5 is an admission of that. But as failures go, it’s pretty good, being that it will be the backbone of what is generally regarded as the most significant development for Apple’s platforms since the announcement of the original iPhone.
I, for one, wouldn't be surprised at all if Apple had a long term plan when they designed Push Notifications. I certainly thought they were kind of a half-baked way to do just notifications, but in the context of iCloud now, it sure makes the whole thing look amazing.