Icinga is based on Nagios, quite a large user base

Whatever, my understanding, as no one can cover every solutions (here monitoring), were you choosed one solution (here Zabbix) and only one to be available on another subjects.
You talk about pulling information from the monitoring solution. Is pushing still on the road map ? Here is an example of what i mean :
- You're an Opennode administrator living in los angeles
- Alice, your friend, is an Icinga administrator living in New York
One day, because you are in a good mood, you decide to create a vm on OpenNode called "Damned good Windows VM"
=> Alice will see in her Icinga monitoring panel, a new node appear and called "Damned good Windows VM" on which an automatic autodiscovery service is started. The discovered services are HTTP, HTTPS, SMTP, IMAP, LDAP in this example. As a result, these informations are given back and you in Los angeles, in front of OpenNode, you see that your "Damned good Windows VM" is now populated with new informations corresponding to the discovered services. You also could follow the provided link to go into Icinga and directly to the "Damned good Windows VM" node for the details.
This is a "add event", that is create a node on OpenNode, Icinga is informed and start adapted process to give back results to OpenNode.
There are other events in OpenNode like suppressing a vm, renaming a vm.
There are other events in Icinga like services changing on a given node over time.