When Mir was announed, Wayland was already past 1.0. About 60% of the GNOME applications currently run under Wayland. See https://live.gnome.org/Wayland/Applications.
Note that Mir requires the exact same stuff. Just that nobody posted a patch to add such support. It is all distro specific.
Re:Ubuntu 13.10 to ship with Mir instead of X
by mercurial on Friday July 12, 2013 @07:58AM
(#6032116)
Not going to be integrated in upstream KDE in any case, see [1]. I don't think Gnome devs are particularly sanguine about it either.
As for me, I'm waiting for a hypothetical WLMonad.
1: http://blog.martin-graesslin.com/blog/2013/05/mir-in-kubuntu...
Qt5 now works on Wayland - and KDE has a release coming up (the dev code already works on Wayland)