A desktop file is now being bundled with the GNOME Shell to add support running Wayland under gnome-session. This modest but important change is part of the Wayland enablement plans for GNOME 3.10 and as serving as a Wayland tech preview in Fedora 20.
The desktop file is able to auto-start the GNOME Shell / Mutter running on Wayland. The command carried out by the desktop file is mutter-launch -- gnome-shell-wayland --wayland. Overall, the GNOME 3.10 support for Wayland is in good shape and should satisfy enthusiasts wishing to try out Wayland with a real desktop for the first time. On Fedora 20 it should just be a matter of selecting the Wayland session from the GDM log-in screen.
The commit adding the desktop auto-start file can be found here. There's also the related bug report concerning GNOME Shell running as a Wayland compositor.