Google updates info on Android 4.2 development
The Level 17 APIs cover Daydream, the new interactive screensaver mode for Android devices, the use of secondary displays, lock screen widgets, nested fragments, support for multiple users, Renderscript, and support for languages that use right-to-left (RTL) UIs…
For API Level 17, it writes:
As an app developer, you should download the Android 4.2 system image and SDK platform from the SDK Manager as soon as possible. If you don’t have a device running Android 4.2 on which to test your app, use the Android 4.2 system image to test your app on the Android emulator. Then build your apps against the Android 4.2 platform to begin using the latest APIs.