This could help solving the following example:
I have the following types of hosts:

- hostA1...hostA10 - Front-end running apache + squid + iptables + auth daemon + parameters client1
- hostB1...hostB5 - Front-end running tomcat + squid + iptables + auth daemon + parameters client1
- hostC - Back-end CMS server running apache + squid + auth daemon + parameters client1
- hostD - DB server running mysql + auth daemon + parameters client1

Now I want to create the same environment for client2, so everything should be the same except the "parameters"

From the IRC discussion:

<ohadlevy> marcellods: so you want to include them all in another hostgroup, just that you could share the params?
and what you do today, is simulating that, simply by riding the domain concept to do the same, 
and I think that the right concept, is an organization, where each org is a different customer