Yes, the Hadoop cluster is running at this point, but the monitoring programs that are installed by HMC (ganglia and nagios) are not running. If you wish to get these running as well then what you can do is:
1) close the browser page pointing to the HMC install/uninstall
2) in a terminal / command line enter 'yum erase hmc puppet -y'
3) then 'yum install hmc -y'
4) rerun the HMC install by pointing browser to 'http:///hmc/html'