Android 8.0 Oreo has been out for a couple of weeks at this point of time and hasn't actually available to each and every Google Nexus and Pixel smartphone out there yet. However, amidst that, the next iteration of the OS has been revealed as Android 8.1.
This information is coming via a teardown of the Google app v7.11 beta done by Android Police. However, it is important to note that this information has been presented on the basis of speculations and guesswork.
Apps are typically configured based on the SDK and according to the publication, the tear down has unveiled that at least some of the developers from Google are using the Android 8.1 SDK for building apps. The same thing had also happened last year also when the next edition of Android 7.0 Nougat was followed up by Android 7.1.
As for the name, it makes much sense for Google to keep using Oreo and it's also how it did things last year with 7.0 and 7.1 both being Nougat. For the when Android 8.1 will hit the market then remember that in 2016 Android 7.1 debuted with the Pixels only a couple of months or so after 7.0 updates started going out. So it is speculated by GSM Arena that this year the second-gen Pixels will be the first devices to launch running Android 8.1 when they land in October.
Android 8.0 Oreo has revealed a number of new features like icon shapes; dots for notifications, more security options, and an auto fill service, smart text selection, and a picture-in-picture mode. However, the developers were having access to the preview version of the Android Oreo operating system since mid-March, with updated versions releasing in May, June, and July.