I just completed installing Zimbra on Openvz on Centos. There is another thread, too, but I am posting here because to the people who will only follow this thread it might create an impression that Zimbra won't work with OpenVZ. I followed it and wasn't going to experiment - but someone convinced me to try and succeeded.
So, here is the How-to:
http://forum.openvz.org/index.php?t=msg&th=375&start=0&
Sincerely,
Chintan Zaveri.