Before trying to compile and run any of the toolkits below, keep in mind that they're all in progress and at most at the prototype stage. While the Wayland core protocol has been stable for some time, experimental protocols extensions are still changing.
Wayland support in the Qt 5 toolkit is happening in the Lighthouse wayland plugin. To try it out check Qt 5 Wayland instructions.
Many recent versions of distributions package GTK+ where Wayland support is enabled. For more information about Wayland support in GTK+, check the GNOME Wiki page.
The Clutter toolkit uses GDK as a backend by default in recent versions and as long as GDK supports Wayland, so will Clutter. It also has its own experimental Wayland backend. For information about how to build Clutter, check check the GNOME Wiki page.
Experimental Wayland support was added in SDL 2.0.2, disabled by default.
The EFL port to Wayland is under active development - Ecore, Evas and Elementary have backends that target Wayland for both SHM and EGL based presentation. Full details can be found in the EFL instructions