While there are a lot of technical changes in this build like adjustments to the API and debugging support for Clutter OpenGL, there are lots of performance improvements, much improved documentation, build environment fixes, and other improvements too. Clutter's input devices API has been improved and does support X Input 1.x (must be configured through a build-time option), while support for X Input 2 will be added following the Clutter 1.0 release. When it comes to the programmer's documentation, there is now 99% coverage for the 1600 symbols exported for Clutter and over 80% coverage of the exported symbols for COGL.
Beyond those changes, the full change-log for Clutter 0.9.4 is quite lengthy and can be found in the release announcement. The Clutter Toolkit is licensed under the GNU LGPLv2.1 license and beyond its extensive use within Moblin, Clutter is beginning to be used within GNOME Games and other free software projects.