After two developer previews, Android 8.1 Oreo is ready for the masses. Google announced that the new OS is rolling out now and is posting system images for the Pixel 2 and 2 XL, the Pixel 1 and 1 XL, the Pixel C tablet, and the Nexus 6P and 5X. The Android Open Source Project (AOSP) code drop should be happening now, too.
Android 8.1 Oreo is a minor maintenance release after the major update of Android 8.0. The biggest feature in 8.1 is a new "Neural Networks API" (NNAPI), which is designed for running machine-learning operations on mobile devices. Phones with specialized machine-learning hardware can hardware accelerate this API, while older devices can use a CPU fallback mode. The API provides a base layer, higher-level, machine-learning framework to plug into, like Google's TensorFlow Lite.
One of the first phones to ship with one of these special machine-learning co-processors for the NNAPI is the Pixel 2, which is packing a custom, Google-designed eight-core SoC called the "Pixel Visual Core." This is Google's first-ever consumer SoC, and it lives alongside the usual eight-core Qualcomm Snapdragon 835. The Pixel Visual Core—which was designed with help from Intel—will power NNAPI functions, and it allows Google's HDR+ image processing to run "5x faster and at less than 1/10th the energy." It shipped in a dormant mode when the Pixel 2 was released, but with the release of Android 8.1, Google is turning it on for everyone.
Android 8.1 also marks the release of "Android Go" for OEMs. Google's "Go" initiative strips down the Android OS and many of the Google apps to run better on low-end devices with 1GB of RAM or less. Google is chasing "the next billion users" with this move, a reference to the 3.5 billion people in the developing world that will access the Internet for the first time from a low-end smartphone.
8.1 also brings a few tweaks to the existing Oreo formula. Bluetooth battery levels are slowly creeping into Android. 8.1 finally adds a battery readout to the Bluetooth Quick Settings and the Bluetooth regular settings, which is a good start. You'd really want the Bluetooth battery level in the status bar, but for now that's not present. Google is also adding some burn-in mitigation to the system bar. The always-on bar will turn to an inverted black-on-white color scheme in some apps like the system settings and Google Maps. The idea is that changing up the color scheme will reduce burn-in for this always-on UI component. The system buttons also dim after a second or two of idleness.
You get new hamburger, beer, and cheese emojis in Android 8.1. Google's weird cheese-on-the-bottom hamburger construction went viral in October, and this release makes good on Google's promise to fix it. The old beer emojis were impossible, with foam magically floating atop a half-full beer glass.
Once Google pushes out all the update files, Android 8.1 can be had via flashing a system image (which will do a full wipe), flashing an OTA image (for an in-place upgrade), or mashing the "update" button in the settings.