under gentoo, emerging new 0.6.3 version, here is the compilation error i
encountered :

gcc -DHAVE_CONFIG_H -I. -I. -I.. -D_GNU_SOURCE -D_LARGEFILE_SOURCE
-D_FILE_OFFSET_BITS=64 -I/usr/include/libxml2 -pthread
-I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -I.. -Wall -Werror
-DGST_DISABLE_DEPRECATED -g -I../libs -I../include
-DG_LOG_DOMAIN=g_log_domain_gstreamer
-DGST_CACHE_DIR=\"/var/lib/cache/gstreamer-0.6\" -mcpu=athlon-xp -O2 -pipe
-MT libgstreamer_0.6_la-gstplugin.lo -MD -MP -MF
.deps/libgstreamer_0.6_la-gstplugin.Tpo -c gstplugin.c  -fPIC -DPIC -o
.libs/libgstreamer_0.6_la-gstplugin.lo
gstplugin.c: In function `gst_plugin_load_plugin':
gstplugin.c:183: warning: dereferencing type-punned pointer will break
strict-aliasing rules
make[4]: *** [libgstreamer_0.6_la-gstplugin.lo] Erreur 1
make[4]: *** Attente des tâches non terminées....
gcc -DHAVE_CONFIG_H -I. -I. -I.. -D_GNU_SOURCE -D_LARGEFILE_SOURCE
-D_FILE_OFFSET_BITS=64 -I/usr/include/libxml2 -pthread
-I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -I.. -Wall -Werror
-DGST_DISABLE_DEPRECATED -g -I../libs -I../include
-DG_LOG_DOMAIN=g_log_domain_gstreamer
-DGST_CACHE_DIR=\"/var/lib/cache/gstreamer-0.6\" -mcpu=athlon-xp -O2 -pipe
-MT libgstreamer_0.6_la-gstpad.lo -MD -MP -MF
.deps/libgstreamer_0.6_la-gstpad.Tpo -c gstpad.c -o
libgstreamer_0.6_la-gstpad.o >/dev/null 2>&1
mv -f .libs/libgstreamer_0.6_la-gstpad.lo libgstreamer_0.6_la-gstpad.lo
make[4]: Leaving directory
`/var/tmp/portage/gstreamer-0.6.3/work/gstreamer-0.6.3/gst'
make[3]: *** [all-recursive] Erreur 1
make[3]: Leaving directory
`/var/tmp/portage/gstreamer-0.6.3/work/gstreamer-0.6.3/gst'
make[2]: *** [all] Erreur 2
make[2]: Leaving directory
`/var/tmp/portage/gstreamer-0.6.3/work/gstreamer-0.6.3/gst'
make[1]: *** [all-recursive] Erreur 1
make[1]: Leaving directory
`/var/tmp/portage/gstreamer-0.6.3/work/gstreamer-0.6.3'
make: *** [all] Erreur 2

"warning: dereferencing type-punned pointer will break strict-aliasing
rules" feels like a bug exposed by gcc 3.3.x only (should have been a
warning under 3.2.x)