I have neglected cluttermm recently (a C++ API for Clutter). But Chris Kühl has recently fixed several cluttermm problems shown by example code in the cluttermm version of our tutorial and updated the tutorial itself. I’ve also added new API to wrap the new ClutterAction, ClutterActorMeta and ClutterEffects stuff in clutter 1.3/1.4. I’ve done new tarball releases to get the fixes out into the world. So I think it’s looking fairly healthy again, though I hesitate to call it stable before more people are using it.
The cluttermm API documentation is another good starting point.