After upgrading to Fedora 17 from 16 via Preupgrade I've had an issue with the non-free portions of GStreamer not being 'seen' by any media players that rely on it. gst-launch-0.10 complains about missing decoders as well. All of the libs seem to be in place (in /usr/lib64), and I have all of the most recent free, and non-free, gstreamer packages from rpmfusion. Anyone have any ideas what might be causing this issue?
Here's a load of debug information from gst-launch if it helps:
http://pastebin.com/PDcGX5Ht