This week a Unity 8 / Mir PPA was made for Ubuntu Touch via the Launchpad Phablet Team. This PPA for now is a separate but parallel build of Ubuntu Touch and the shell is quite limited and doesn't support application launching, but it's a start for those wanting to be among the first to try Unity 8 and/or Mir.
This week, Mir's APIs were changed to cater towards Unity 8's window management needs with regard to focus control, visibility, and other needs. Also added this week to Mir was support for a buffer-swapper mechanism, surface snapshots for transition effects, various bugs, GPU back-ends are more pluggable for Mir, and progress on Android composition bypass.
The status updates on Mir / Unity 8 were shared in a weekly status report on the ubuntu-devel list. Being planned for next week is more work on Unity 8 window management with Mir, merging unity-system-compositor LightDM changes back into Mir, creating Bzr repositories for needed Mesa/Xorg patches, and more Mir-on-Mir development. Canonical developers are also starting to look at XMir multi-monitor support.