Matthias Clasen of Red Hat has been one of several developers recently working on the Wayland back-end to the GTK+3 tool-kit. Clasen spent most of the past two weeks working on Wayland GTK+ support and getting it into shape for "day-to-day usability" by Linux desktop users.
Among the work that's now in good shape is GTK+ client-side decorations, GTK+ applications picking up desktop settings now directly through GSettings, improved keyboard support (key repeat, reading keyboard settings from GSettings, keyboard state information propogation, etc), handling of keyboard layout changes, support for custom title-bars, and more.
While GTK+ 3.8.0 was released yesterday with Wayland 1.0 support, all of this brand new work by Clasen and others is currently living on GTK+ master.
Clasen's blog post and the Wayland GTK+ Wiki.