I would like to add that in FC2(default) the plugin dir is:
/usr/lib/mozilla-1.6/plugins (case in which all users have access to it)
I'd rather recommend using
/usr/lib/mozilla/plugins/
instead of the version-specific /usr/lib/mozilla-1.6/plugins !!
Should you ever update mozilla to something other than 1.6 (this did happen with RH9), you'll end up losing your plugins if they were living in the version-specific dir. whereas if you placed them in the generic /usr/lib/mozilla/plugin dir, they would stick around after the upgrade !
Just my $0.02 :)
Gabriel