Android O Developer Preview 4 is available for Nexus 5X, Nexus 6P, Pixel, Pixel XL, Pixel C, and Nexus Player. And this is what Google says for the next final release :
As we put the finishing touches on the Android O platform, today we're rolling out Developer Preview 4 to help you make sure your apps are ready.Google released final Android O APIs in the previous Developer Preview, so it is encouraging developers to test their apps against these mature hooks to make sure that, when Android O is publicly released in the next few weeks, apps take advantage of new features like notification channels, background location limits and an improved implementation of Doze.
This is the final preview before we launch the official Android O platform to consumers later this summer. Take this opportunity to wrap up your testing and publish your updates soon, to give users a smooth transition to Android O.
This is what the new update introduce for developers :
We're releasing the Developer Preview 4 device system images today, together with the stable version of the Android 26.0.0 Support Library. Incremental updates to the SDK, tools, and Android Emulator system images are on the way over the next few days.
We're also introducing a new version of Android Testing Support Library that includes new features like Android Test Orchestrator, Multiprocess Espresso, and more. Watch for details coming soon.
Here’s what Google is saying:
Developer Preview 4 is a release candidate build of Android O that you can use to complete your development and testing in time for the upcoming official release. It includes the final system behaviors, the latest bug fixes and optimizations, and the final APIs (API level 26) already available since Developer Preview 3.
You can download the update either from the OTA if you have enrolled in Android Beta Program or you can have it via factory image below :
We’ll flash ourselves and let you know of any big changes!
Source : Android Developers