Mir was already ditched from Ubuntu 13.10 on the desktop by default due to outstanding issues. An X.Org Server will still be the default for Ubuntu 13.10 on desktops while Mir can be optionally installed from the package archive. In the Ubuntu Phone world, Canonical feels Mir is ready to take on the world and replace Android's SurfaceFlinger in their stack.
Yesterday I wrote about the recent landing of Unity 8 UI in Ubuntu Phone and Mir on finals for landing. That last update had Mir as a top priority of focus on Monday, while now on Tuesday morning Mir isn't yet officially landed.
Loïc Minier's latest status update on the mailing list from hours ago says, "On the Mir front, progress was good over Monday and the input issue has a candidate fix, but it seems to affect ubuntu-keyboard. Once this is understood, this should go in and help address the input related issues we were facing so far. The upstart memory leak with device specific events is also making good progress. The runway is clear for Mir to land along unity-mir and upstart-app-launch updates to get us the final app management experience!"
So while it's not landed yet, it sounds like it should be imminent barring any new problems. In the past day Ubuntu Phone was also able to take care of two sets of new regressions, Unity 8 updates, and some apps were converted from .deb packages to the new Ubuntu .click packages. The latest Ubuntu Phone image also adds the Click framework for the Ubuntu 13.10 SDK.