Mir 0.2.0 is the new, work-in-progress version of this open-source display server for Ubuntu Linux. The version was bumped for reflecting early development of Ubuntu 14.10, the Utopic Unicorn.
This morning the Mir Server library ABI version was also bumped. "Bump server ABI to 20, as we've already got around 2000 lines diff of header
changes since release 0.1.9." Well, it's better late than never.
While Mir is currently powering Ubuntu Touch/Phone, it hasn't yet replaced the X.Org Server as the default on the Ubuntu Linux desktop. When it ultimately will is not clear -- just that it will be the default by Ubuntu 16.04 LTS after originally having lofty goals of shipping Mir by now on the desktop.