rpm -Uhv http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
yum install munin-node

As you attempt to install Munin node on CentOS 6.4 from EPEL repository, you may encounter following error message:

Transaction Check Error:
  file /usr/share/man/man3/XML::SAX::Base.3pm.gz conflicts between attempted installs of perl-XML-SAX-Base-1.04-1.el6.rf.noarch and perl-XML-SAX-0.96-7.el6.noarch
  file /usr/share/man/man3/XML::SAX::Exception.3pm.gz conflicts between attempted installs of perl-XML-SAX-Base-1.04-1.el6.rf.noarch and perl-XML-SAX-0.96-7.el6.noarch

Simply install perl-XML-SAX-0.96-7:

yum install perl-XML-SAX-0.96-7.el6.noarch

and now you can install munin-node without any error message:

yum install munin-node