the mp3 plugin seems to be installed but audacious ( the freeworld-mp3-2.4.0-1.fc14.x86_64) doesn´t seem to recognize it . Can someone tell me what´s going wrong ?
The freeworld plugin comes from rpm-fusion, not from Fedora. You need to enable the rpm-fusion repo and then do an update:
# yum --enablerepo=rpmfusion-free* update audacious-plugins-freeworld-mp3
If you look carefully at the packages you list, you can see that the freeworld package is an older version than what you just updated "audacious" to.
--Greg