On CVS HEAD (but not 0.7.5) running gst-register as a user registers twice
as many plugins as when running it as root, registering everything twice,
once in /var/cache/gstreamer-0.7/registry.xml and again in the home
directory.  After running gst-register, most plugins work, but, for
example, using spider causes crashes.  E.g.:

[jat48@thacker jat48]$ gst-launch filesrc location=test.ogg ! spider ! alsasink
RUNNING pipeline ...
 
** (process:5530): CRITICAL **: how to remove plugins?
 
(process:5530): GStreamer-CRITICAL **: Factory for `oggdemux' has no type

This plays fine if the file ~/.gstreamer-0.7/registry.xml is erased, and
gst-register isn't run.

Output of gst-register and gst-feedback attached.  As a side note,
gst-feedback also complains about gstreamer.pc and gstreamer-libs.pc
missing, since by default only gstreamer-0.7.pc and gstreamer-libs-0.7.pc
are installed into /usr/lib/pkgconfig