Android 8.0 is officially Android Oreo
Because that's how the cookie crumbles.
We've known for some time that the eighth iteration of Google's Android OS was imminent and that it would be Android "O" because Google has used iterating alphabetical order for its Android releases to date. That's why Android 7 was N and Android 6 was M.
Letters are dull and hard to brand with, so Google has also used dessert names for its Android releases, with most pundits picking that "O" might stand for "Oreo", even though that's a trademarked name. However, Google has form there, too, with Android 4 ("K") being KitKat.
Google officially released Android 8.0 overnight, and indeed, it's Oreo-branded. It even has its own silly announcement video to boot.
What's new in Android Oreo?
Like many new Android builds, a lot of what's actually new in Android Oreo is in the form of under-the-hood optimisations that you won't automatically see if your Android device gets the upgrade. However, there are some smaller scale changes that will be apparent, including an updated settings app layout and larger features such as floatable picture-in-picture windows, although at the launch of Oreo, there's not a huge quantity of app support for that feature. Expect that to change fairly rapidly.
Autofill has been refined to work with password managers, and most of the major apps have already announced support for Oreo's autofill features. Notifications have changed, with the default notification shade now in white (maybe that's the Oreo cream poking through?) and notifications themselves have been visually tweaked. Speaking of visual tweaks, Android Oreo will also feature a new range of emoji to pick from.
How can I get Android Oreo?
As it has with previous releases, Google's holding Android Oreo as an exclusive for its own in-house devices, at least at first. Specifically, it's only currently compatible with the Nexus 5X, Nexus 6P, Pixel, Pixel XL, Pixel C and Nexus Player devices. If you head to your system settings and poke System Updates, you'll most likely be told that you're already running the latest updates, presuming that you've been keeping your Android devices up to date. That's especially true for vendor-supplied devices, such as the Telstra-specific Pixel and Pixel XL, which will (officially speaking) have to wait for the official OTA updates to pass through Telstra's testing labs.
That being said, if you want to force the issue, it's possible to at least try to upgrade a compatible device by signing it up to Google's Android Beta program, which you'll find here.
We should stress that this is an experimental route, and it's essential that you back up all your data before upgrading. Actually, you should do this before any major system update anyway. Heading there and signing into your Google account should reveal any compatible devices linked to your account, and linking them should make the update available almost immediately. We tested this with a Pixel C tablet, and the update appeared before we'd even closed the web page.
I don't have a Google-branded Android device. How long will I have to wait?
That's an incredibly open question because Android updates are fraught with fragmentation. Some devices see multiple updates, and some only see security updates. In fact, some are never updated at all.
As a rough rule of thumb, more premium devices tend to see updates more rapidly than budget ones, although some providers, such as Nokia/HMD have committed to Android updates for their lower-cost devices. Still, the official wait could be a long one. The open nature of Android does mean that enthusiast builds of Android releases are sometimes developed for specific handsets, although that's a path that can be technically tricky to adopt and isn't vendor-supported.