The wait for Xposed Framework on Android 8.0 and 8.1 Oreo is over, but the product is currently in a rough beta form. This is the very first release for Oreo, and comes only a few months after a version for Android 7.0 Nougat that had taken about a year to complete. Naturally, with the move from Nougat to Oreo making some serious changes to the Android core codebase, some modules may not work right just yet. Two of the most popular, device customizer GravityBox and battery optimizer Amplify, are already fully modified and ready to go. The framework itself is still in beta at this point, and there most likely will be bugs. Keeping that in mind, developer rovo89 has asked that the community submit reports only on easily reproducible bugs, preferably involving a minimum of variables like kernel modification.
The new version is compatible with all devices on Android Oreo, so long as they can be rooted; that's a prerequisite for installation on devices and Android versions. If your device meets the prerequisites, you simply need to root it and flash a custom recovery like TWRP to do the installation. Install the Xposed Installer APK from the source link, and download and flash the appropriate Xposed Framework ZIP file according to your Android version. It should go without saying for anybody who's experienced enough with root to want to do this that there is an inherent risk; if you flash the wrong file or your device powers down during flashing, it may well become inoperable. Likewise, trying to use this without root may result in unexpected behavior, though it will most likely just be ineffective.
For those not in the know, Xposed Framework has been around since 2013, and has been available for just about every major Android release since Android 4.4 (KitKat). It allows you to use custom modules that change system functionality in a number of ways, from simple things like changing how your device handles battery usage per-app and enabling custom gesture controls to more complicated fare like replacing your navigation bar with a pie menu and letting you set a custom screen resolution for each app.