Going back numerous months has been a proposal for a full-screen shell protocol initially for the Weston compositor but could be promoted to an official Wayland protocol in the future. The fullscreen shell protocol is designed to make it easy to support simple full-screen clients like splash screens and terminal emulators in an easy and convenient manner rather than having the simple clients talk to DRM/KMS directly, input/output abstraction, easing up development of compositors, and allowing support for screen sharing and recording.
As of yesterday there's now the fullscreen-shell support support spanned over several commits, a new --sprawl option, and a new screen sharing plugin. This work was led by Jason Ekstrand and other developers. These features will be part of the upcoming Weston 1.5 compositor release.