We're getting very, very close to the release of Android O. Google has put out three developer previews for Android O, and today is the fourth and final dev release. The OTA for devices in the Android Beta Program is rolling out as we speak, and there are system images so you can flash the new preview manually. This one should be representative of the final build.

According to Google, this update is a release candidate with final system behaviors, the latest patches, and the final APIs that will launch with Android 8.0. There shouldn't be any obviously broken things at this point, so it might be stable enough to use as a daily driver until the final release happens. For developers, this is your last chance to test apps and get your updates published before regular users start getting Android O.

You can still enroll an eligible device in the beta program, or simply grab the updated system images. Those already running developer preview via the beta program should get the OTA to DP4 today, although it's not showing up on my test phone yet. The O Developer Preview is available on the Pixel, Pixel XL, Pixel C, Nexus 5X, Nexus 6P, and Nexus Player.

Google is only saying the final update will launch "later this summer," but we're probably a month or so out. That's also when we'll know for certain what the O code name will be.

Source: Android Developers