Google teased that Android 8.1 would be getting a developer preview shortly, when it announced Pixel Visual Core last week. Which is basically the brains behind the camera in the Pixel 2 and Pixel 2 XL. Well now, the search giant has unleashed Android 8.1 Oreo in the form of a developer preview. The factory images are now available, and OTA's should begin rolling out shortly for those that are in the Android Beta Program. As was the case with the Android 8.0 Oreo developer previews, Google is supporting the Nexus 5X, Nexus 6P, Pixel C, Pixel, Pixel XL, Pixel 2, and Pixel 2 XL, so no devices are getting dropped with this update - which isn't a surprise.
With this being a .1 update for Android Oreo, there's not a lot of big, user-facing features here. Google has added quite a few changes to API's and a few new ones. One of the more interesting ones here includes improved targeting for low-RAM devices. It essentially allows developers to target skinny APKs to those with less RAM versus those with a decent amount of RAM on their devices. This is all part of Google working to make Android work better on devices with less RAM, something it's been doing for a few years now. Google has also updated the Autofill framework that debuted in Android 8.0 Oreo, as well as the EditText method.
In Android 8.1 Oreo, you'll find a few new error codes for the FingerprintManager as well. There is one that appears when you try to unlock your device using the fingerprint too many times, and another that is vendor-specific. These, of course, won't really affect the user, and most users won't even see these errors on their devices with Android 8.1 Oreo.
Google hasn't put out a firm release date for the stable version of Android 8.1 Oreo just yet, but it is expecting it to be available in December, barring any show-stopping bugs of course. Keep in mind that if you were in the Android Beta Program for Android 8.0, you will need to re-enroll for Android 8.1. At the time of writing this, it appears that the switch hasn't been flipped for the OTA to begin rolling out just yet, but that should happen imminently.