It looks very interesting. It feels like Nagios but seems to be easier.
I used Hobbit. It is based on Big Brother. Definetively easier to use than Nagios. I tried 3 before deciding for it. Points that won it for me were.
Deployment was easier than Nagios. Requires a bit of time to learn it, but it can be set in a day (I can set it now in less than an hour).
easy to add services (it is done thru a config file, which I would open with programer's notepad and copy paste settings to add similar services.
It is not required a client. Thought with it can be faster gathering, and allows more check. The client is also used to check on logs in a secure manner (not needing to access the logs remotely).
1 Page all status, which option to see more in detail.
Clients pull configuration from server, not needing to modify client by client when changes are made.
This said, I would test Zenoss if I have a project were I need to monitor a network, but for what I read Zenoss and Hobbit could be complemented.
Hobbit doesn't use SNMP, thought it could be implemented into it.
Big advantage of zenoss is having a virtual appliances which makes it fater to have it running (for testing pourposes or to show to upper management)
This is how I got the hobbit running as well, but I installed it in the VM appliance. I was able to copy the configuration thought, so passing from a virtual appliance to a server took about 30 minutes (installation + configuration of IP and preparing the server)
Rik, could you provide your experience with Zenoss? Does it need a dedicated server?