Comment # 25 on bug 57875 from Piero Finizio

 Stefan Dösinger you are right: the bug didn't disappear; for some reasons the
change of environment for mesa directory doesn't work on FC18 simply with

"/etc/ld.so.conf.d/a-local-xorg.conf (new file) or add to begin of
/etc/ld.so.conf if directory doesn't exists:
/usr/local/lib

and to /etc/environment  to add new environment variable that tells libgl where
to look for dri drivers (example r300_dri.so):
LIBGL_DRIVERS_PATH=/usr/local/lib/dri/"

so I had  to link /usr/local/lib/dri/r300_dri.so to /usr/lib/dri/r300_dri.so

Sorry for the  inconvenience.