Can ZenOSS integrate Ganglia smoothly?

Since I see the nagios tag in your question, did you consider integrating Ganglia and Nagios? If so, take a look at this:

1. http://www.ibm.com/developerworks/linux/library/l-ganglia-nagios-1/
2. http://www.ibm.com/developerworks/linux/library/l-ganglia-nagios-2/

In the Ganglia source code folder, there is a script named check_ganglia.py which can be used as a Nagios plugin to report on Ganglia metrics.

define command {
    command_name    check_ganglia
    command_line    $USER1$/check_ganglia.py -h $HOSTNAME$ -m $ARG1$ -w $ARG2$ -c $ARG3$
}

An example of definition to monitor CPU system:

define service {
    use                     generic-service
    hostgroup_name          ganglia-servers
    service_description     cpu_system
    check_command           check_ganglia!cpu_system!70!80
    max_check_attempts      5
    check_interval          5
    retry_interval          3
    check_period            24x7
    notification_interval   60
    contact_groups          admin
}