Apple for the day

ZDNet has an article by Adrian Kingsley-Hughes about the Apple Watch:

Apple's newly released WatchKit documentation offers us an insight into how the new class of device will look, feel, and work. I've been digging through the documentation looking for clues as to what the new device has to offer and what new features it will bring to the Apple ecosystem. We get the screen sizes and pixel densities for both sizes of Apple Watch (photo, above). App designers will have to design the app to work on both screen sizes; both fall into the Retina Display category.
Apple is introducing a lot of new concepts when it comes to interacting with the Apple Watch (and how the Apple Watch interacts with its owner). 

Digital Crown: a twist on the traditional crown on a watch. Allows for scrolling through longer pages of information.
Digital Touch: the Heartbeat and Sketch features that allow for personal communication.
Taptic Engine: subtle, physical feedback associated with alerts and onscreen interaction.
Force Touch: a physical gesture (in other words, a press) interpreted by hardware. The display not only detects a touch, but can also sense the force.
Short Look notification: a minimal alert that only displays more information "if the wearer remains engaged".
Glances: information displayed by apps in an easy-to-access, swipe-able interface. 

Apps will not run native on the Apple Watch, at least not initially. Instead, when the user taps on an app on their Apple Watch, it launches a WatchKit extension on their iPhone and connects to each other that way. This allows messages to be sent from the app on the iPhone to the app on the Apple Watch until the user stops interacting with the app.
Not only does this transfer the bulk of the work to the iPhone, it means less of a battery drain on the Apple Watch (although how much additional battery drain this will put on the iPhone remains to be seen).
Apple is offering two layout styles for apps:

Hierarchical: this will be similar to how the Mail app works in iOS.
Page-based: similar to how the Stocks or Weather app works under iOS.

Apps will support simple menus, which allows developers to make better use of the limited screen real estate. Users will be able to bring up menus using the Force Touch gesture. However, they are not scrollable so they can't be used too heavily.

Rico says it is only by severe restraint that he does not refer to it as an iWatch, but it looks like it'll be a cool thing to own...