Canonical's Christopher James Halse Rogers published a set of nine patches on the Mesa developers' list a short time ago. The patches are authored by Christopher and fellow Canonical employee Maarten Lankhorst. The patch-set is basically about supporting DRI Image 6/7 in the Gallium3D drivers.
The drivers enable DRI Image 7 support for the Gallium3D drivers currently supporting DMA-BUF's import/export capabilities: Nouveau, LunarG's ILO Intel Gallium3D, and Radeon (R300, R600, and RadeonSI). There's also the necessary prep work to Gallium3D's driver-independent DRI and DRM winsys code. This isn't some brand new innovation out of Canonical but they are patches that (in earlier form) have been proposed several times in recent months by Christopher James Halse Rogers on the Mesa developers' list.
The set of patches are needed for supporting Mir's EGL platform in mainline Mesa. Additionally, the code can be beneficial to Wayland's PRIME support with DMA-BUF import/export handling and also DRI3. Canonical originally published the Mesa patches for Mir support back in March but there haven't been many upstream Mesa developers to comment on them one way or another. The Mesa Mir support for use by Ubuntu Linux as found in Ubuntu 13.10, etc, is maintained by out-of-tree patches in the packages.
With the Mesa 10.0 merge window now closed we'll see in the coming days if Canonical tries to mainline their Mir back-end itself for Mesa or just simply is trying to reduce the maintenance workload in supporting the out-of-tree code by pushing forward some code (i.e. today's patches). As Ubuntu 14.04 won't be using Mir/XMir, there's plenty of time ahead for patch wrangling.
The patches in their latest form can be found on the Mesa-dev list.