I would like to note an underexplored territory that is ripe for the munching, the "southern buttermilk biscuit -- mallorcan sobrassada" interface. Spreadable sausage on a biscuit. God did truly shine his face on my kitchen this morning.
I got guile-gstreamer working today, which is hot. Version 0.9.90 is totally released. The last bit that I had to do was to leave "guile mode" when the wrapper calls C functions, and to enter guile mode when GClosures are invoked. That is what it takes to be thread-friendly with Guile; while multiple guile threads can be running at the same time, they have to not block, because GC or thread joining requires cooperation from all threads.
So, multithreaded GStreamer and Guile. I'm pleased, this is already more than the old 0.8 wrapper did. Also the process of porting to 0.10 was mostly removing crufty code, which says nice things about the state of GStreamer-the-library.