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, just for you. The "short look" for the notification provides a minimum of information. Nothing for anyone else to spy, just the icon for the app that's notifying a brief bit of context as to who or why. If you lower your wrist, it goes away. If you don't, or if you tap it, it expands into a "long look" and gives you the details. That kind of staging respects that with greater intimacy comes greater responsibility. And I hope that it's a sign of more features to come.
Part of the reason I quickly stopped wearing my Pebble and haven't had much interest in other smartwatches is exactly that lack of discretion and/or granularity — that understanding that the closer something is the more subtle and sophisticated it needs to be.
Privacy, like security, comes at the cost of convenience. 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 VIP anyway, but if I have my iPhone out in public an 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 any incoming messages or mail. There are situations, both personal and professional, where I just don't want that to happen. So, I typically turn previews off. (Even then, they can still see who's messaging me, but without that information I couldn't decide which notifications can and can't be ignored — again, the cost of convenience.)
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 picking up your notifications anyway — but a short look that only expands into a long look if the motion co-processor feels it getting picked up, or the multitouch screen detects a tap event, is still really interesting to me. It would remove the burden of having to micro-managing privacy from me and have iOS just take care of it. Moreover, it would make that kind of privacy protection 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 around us, but the thought process and technologically being surfaced in the Apple Watch will change the way that world interacts with us.