Mark Thomas shared his work to "get MATE fully working on Wayland" and this weekend he took to porting mate-panel to Wayland. Mark mentioned this work now since with the mate-panel it depends upon the ability to share surfaces between GTK processes, which isn't something currently supported by the Wayland protocol.
Wayland doesn't support the GtkSocket/GtkPlug interface and since the MATE Panel code relies heavily upon this functionality, Mark Thomas took to coming up with an interface to support this within Weston. In particular, Wayland needs to understand the concept of linking together multiple clients' surfaces. His proposed implementation introduces a "plug" and "hole" approach for sharing of sub-surfaces between processes.
This code is still a work-in-progress and not yet finalized nor reviewed by upstream Wayland developers, but those interested in this work to eventually bring MATE to Wayland/Weston can read more about it in this Wayland-devel mailing list message.
Meanwhile with upstream GNOME, GNOME 3.12 and its contained components are shaping up to have decent Wayland support with Mutter-Wayland, GTK3, and GNOME Shell after the initial Wayland enablement in GNOME 3.10.