Clutter 0.9 that was just released is a significant update over the earlier Clutter 0.8 build and has major API changes with new effects and capabilities. A horde of bugs have also been addressed. The Clutter 0.9.0 release announcement with change-log can be found on the GNOME mailing list.
Among other applications, Clutter is going to be used for designing the user interface for Intel's Moblin OS. More about the Clutter Toolkit can be found on its project web-site.