Here's how notifications work on the Apple Watch: When a new one comes in, the "taptic engine" — a linear actuator — literally taps you on the wrist to let you know about it. There's no loud buzzing to draw anyone else's attention, just a subtle but recognizable tap, designed for you and you alone. Meanwhile, the "short look" for the notification provides a minimum of information. Nothing that anyone could oversee — just the icon for the app and a brief bit of context as to who or why.
If you lower your wrist, it goes away. Keep your wrist raised or tap the notification, and it expands into a "long look" to give you more details. It's the kind of staging that respects that with greater intimacy comes greater responsibility. And I hope it's a sign of more features to come.
Part of the reason I stopped wearing my Pebble and haven't had much interest in other smartwatches is the lack of discretion and/or granularity when it comes to notifications and privacy — the lack of understanding that the closer something is, the more subtle and sophisticated it needs to be.
Right now, when I travel with my iPhone, I have to consciously think about how much information I want to let leak out onto the Lock screen. I only ever allow mail notifications for my VIP contacts anyway — something I wish I could do for messages as well — but if I have my iPhone out in public and put it down on a table — terrible habit, I know — everyone around me can hear it buzz.
If I have Lock screen notifications left on, everyone glancing at my phone can see the incoming messages or mail. There are situations, both personal and professional, where I just don't want that to happen. As such,I typically turn previews off. (Even then, they can still see who's messaging me, but without that information I can't decide which notifications can and can't be ignored — convenience comes at the cost of privacy.)
Taking a cue from the Apple Watch, it'd be great if the iPhone could also stage my notifications. A taptic engine won't work on a device that isn't always in contact with your skin — and it wouldn't need to if the watch is getting your notifications anyway — but a short look that expands into a long look when the motion coprocessor feels the device being picked up, or when the multitouch screen detects a tap event, that would be really interesting to me. It would remove the burden of having to micro-managing privacy, and have iOS just take care of it. Moreover, it makes that kind of privacy protection freely available to people who wouldn't otherwise know they could micro-manage it.
The contextual awakening of the objects around us might change the way we interact with the world, but the thought process and technology being surfaced in the Apple Watch will change the way that world interacts with us.