[forgottenpass]

The larger idea this fits into is getting rid of X11 all together. The inevitable replacement is Wayland.* One of the challenges of such a switch will that once you start using wayland, you'll have some older applications that cant talk to wayland, you'd have to start an X server to run that old application.

If you have a wayland session on your computer, you don't want to hit ctrl-alt-8 to switch over to an X session running that single application, and then switch back and forth to wayland to use every other program. It would be nice if there was a X server that worked as a wayland client and could put the X-only application on your wayland desktop. That's Xwayland.

* For a better explanation on ditching X, and what Wayland is: see this talk from one of the X dudes working on Wayland http://www.youtube.com/watch?v=RIctzAQOe44

[runeks]

Also, if you've ever run an X11 application inside Mac OS X, you've used something similar: XQuartz.

XQuartz is for running X11 applications inside Quartz (Mac OS X's window server/compositor), XWayland is for running X11 applications inside a window server/compositor that uses the Wayland protocol.