Developers will have three different options for hooking their apps into the Apple Watch. First is the kind of functionality that you'll find on most smartwatches, especially Android Wear, which will let developers create actionable notifications. This means simple interactions, like letting users respond to messages, or more complex actions like controlling smart home products and more. Second is letting developers add information snippets to the Glances screen, which will be similar to the news and sports cards that pop up on Android Wear. Last will be a Watch App, which will have its own interface and features, but will also be able to integrate with iOS features like Handoff, to easily move from the Watch to another Apple device, or AirPlay.
It also looks like the two different sizes of the Apple Watch will feature different resolutions that developers will need to optimize for, as well. The smaller model will have a 1.5-inch display with a 272 x 340 pixel resolution; and, the larger 1.65-inch model will feature a resolution of 312 x 390 pixels.
We're hoping to get to see some demoes in the test environment and see how the Apple Watch will work. It's all starting to happen.