Wayland is the default display server for Ubuntu 17.10 "on supported systems". But how can I tell if my platform is supported and I'm actually using Wayland?
You could install
mesa-utils-extra and run
If the app runs, you are running Wayland.
For a fun way to check whether a specific app is using Wayland or XWayland,
xeyes. The eyes will move if the cursor is over an X or XWayland
Or run this in a terminal:
env | grep -i wayland
If there is no output, you are not running Wayland.