It's been a GNOME development goal for months to have GNOME 3.10 offer a complete GTK+ Wayland back-end and for allowing the GNOME Shell / Mutter to act as a Wayland compositor. The developers have been mostly successful in reaching these goals while going forward in 2014 they still have additional work in moving some code-paths from being X11 specific to allowing Wayland equivalents and other enhancements to this next-generation Linux display server.
The most current state of GNOME on Wayland is described via the GNOME.org Wayland Support Wiki, which was most recently updated this morning. The only GNOME-specific items not in place right now for the GNOME 3.10 release that were scheduled as open tasks for this version were merging a GTK text protocol patch and making the on-screen keyboard send keysyms on Wayland.
The only other open items are building XWayland on Fedora and building Mutter-Wayland on Fedora, both of which should happen for Fedora 20 to lead to a nice GNOME 3.10 experience on Fedora 20 in November/December when using supported hardware/drivers and opting to use this "tech preview" mode.
Other items still being looked at by developers is the Wayland performance not yet being up to par, keyboard accessibility has some issues, and there's a handful of bugs that are considered regressions in GNOME 3.10.