After upgrading to the samba 2.0.5a-1 rpm released on the errata pages for redhat 6.0 the log files in /var/log/samba no longer exist. This is due to the fact that the /var/log/samba directory is removed in the installation of the errata rpm. Fix: manually create /var/log/samba as root.
Alternate fix: do rpm -e samba before installing. It's a problem with the %postun script of the previous version.