2. Actionable notifications
3. Extension WatchKit apps (extension runs on iPhone, view runs on watch)
4. Fully native apps
It appears 1, 2, and 3 will be available for the initial launch, while #4 will be available later next year, probably starting with a beta released at WWDC.
1. Watch App
2. Watch App with Glance
3. Watch App with Actionable Notifications
4. Watch App with Glance and Actionable Notifications
5. "Fully Native Apps"
In other words, you can't have glances or actionable notifications without a Watch app.
You mentioned #4 will be available later next year, probably starting with a beta released at WWDC.
Is Apple actually saying this? If so, can you please share the source? I mean from Apple not macrumors.
"With Apple Watch, developers can create WatchKit apps with actionable notifications and Glances that provide timely information. Starting later next year, developers will be able to create fully native apps for Apple Watch."
Someone from Apple also essentially reconfirmed this earlier today on the WatchKit developer forum.
Edit: here's the source that first tipped me off to this detail hidden away in the press release:
I wonder what fully app for watch means though. I am intrigued on the touch event support. There is something new called Force Touch.
"Force Touch. A small screen can only accommodate so many controls. That’s why Apple Watch introduces an entirely new interaction model: Force Touch. As well as sensing touch, the Retina display also senses force. Force Touch interactions display the context menu (if any) associated with the current screen. Apps use this menu to display actions relevant to the current content." 
I've heard people compare this to a long press, but its subtlety different. Force touch can bring up a context menu faster, because you don't have to wait to determine if a touch is "long" or not
I think there has to be more touch events available than Force Touch. Seems a fairly trivial interaction.
Given the features page I assume the API should support more events. Digital Touch "implies" touch down-move-up:
* Section 6-left, a heart drawn on the watch with the name Jamie.
"You don’t even have to use words. The Digital Touch features on Apple Watch give you fun, spontaneous ways to connect with other Apple Watch wearers, wrist to wrist."
* Below, a flower drawn on the watch with the name Eliza.
"Sketch. Use your finger to draw something quickly. Your friend on the other end can watch your drawing animate, then respond with a custom creation for you."
Hopefully is already there or else we might have to wait and see the touch API public for WWDC. Eager to play with it, if anybody has more information please share. Thanks!
They feature various previously unknown details about the watch, for example that the two sizes have different display resolutions, 340px and 390px respectively.
Edit: better direct link: https://developer.apple.com/library/prerelease/ios/documenta...
"The Watch app resides on the user’s Apple Watch and contains only storyboard and resource files; it does not contain any code. The WatchKit extension resides on the user’s iPhone (inside your containing iOS app) and contains the code and resource files for managing your Watch app’s interface."
This first version is probably just a very early beginning of how the runtime will evolve, to put something out there before launch.
Does this setup significant improve battery performance?
It also has built-in time-display capabilities in the SDK to limit the amount of traffic going between watch and phone (i.e., you don't have to manually update a timer or clock display from your own code, the watch does so locally).
Seems like all of this is meant to reduce processing on the watch side, and also to minimize the amount of data moving between watch and phone.
Not for your phone.
Create prerendered animations using a sequence of static images. Store canned animations in your Watch app bundle so that they can be presented quickly to the user. Canned animations also let you deliver high frame rates and smoother animations. Creating animations dynamically from your WatchKit extension and transferring them to Apple Watch adds a delay before playback can begin.
This is not a good sign as to the power of the watch, unless I'm drastically misinterpreting things.
It takes very little processing power to stream images from memory onto a display. An even more dramatic demonstration of that is http://trixter.oldskool.org/2014/06/19/8088-domination-post-...
Apple wants to limit the frequency of these updates, so the most frequently updated UI bits (clocks, timers) will be done on the device itself without the persistent BT use.
What is probably more constrained is the memory and storage available on the watch. By moving as much of the application to the phone as possible, they decrease the demands on the limited resources of the watch.
That's your opinion. For me it has been life-changing.
Besides that, I mainly use it for "watch" stuff.
That said, it is really nice to be able to get notifications without taking my phone out in certain contexts—bicycling, walking, in a pool, phone charging in other room, etc.
It does use an OLED display and we know black uses less power.
Moreover, there is no way this watch is pulling over 24 hours battery life. They said that they expect you to charge it everyday. In that sense, the power should not be much of an issue as big as the comments here presume. LG G Watch easily lasts 24 hours, and Moto 360 easily goes 16-20 hours. So unless this watch lasts 2 days or more, screwing up the UI makes little sense, you'd be charging it every night anyway.
It'll be fun as a technical exercise and to satisfy one's intellectual curiosity, but not as much fun once you've identified the workarounds for all the constraints and you're just trying to ship.
Here's hoping it will replace Helvetica on iDevices and Macs as well...
IMPORTANT NOTE: THE APPLE SAN FRANCISCO FONT IS TO BE USED SOLELY FOR PURPOSES OF DESIGN AND DEVELOPMENT OF APPLICATIONS FOR APPLE WATCH.
This definitely is designed to maximize battery life
"The Watch app resides on the user’s Apple Watch and contains only storyboard and resource files; it does not contain any code. "
If you wanted to go super-minimal, you could even probably stream a compressed bitmap to a screen that resolution over a wireless protocol, moving all rendering phone-side.
There's also still the issue of the native watch apps coming in 2015.
Edit: You cannot create an Apple Watch project. You create a standard iOS project, then add the Apple Watch storyboard/methods
A brief scan of the documentation didn't show anything obvious.
Can store up to 20 mb.
Frustratating to see products each trying to compete using their own closed ecosystem, because it hurts developers and it hurts innovation.