Mir 0.0.7 was tagged on Monday by Canonical's Robert Ancell within their Bzr repository. In going through the Bzr repository changes since the 0.0.6 release, changes include continued work on testing, updated XMir documentation, GCC compiler workarounds, an XMir infinite loop fix, reduced memory allocations on the front-end, a new DisplayConfigurationPolicy for setting up DisplayConfigurations, and other changes. Mir 0.0.7 also has initial work on making the Mir client API thread safe.
Interestingly, Canonical continues using LLVM's Clang compiler as their preferred compiler for Mir over the GNU Compiler Collection. The expressed reason within commit messages has been better error messages out of Clang. Commits also show they have been using the Clang Static Analyzer on Mir for catching problems.