I installed ZCS 4.0.0 under SUSE Linux 10.1 today
http://kontrawize.blogs.com/kontrawi..._400_suse.html
and didn't have any great issues, just needed to install the packages that Zimbra needs. The installation stops due to a permissions issue with "/etc/sudoers", but it tells you what to fix and how to restart the installation.
I haven't been able to test the setup, as haven't been able to log in to the admin console yet (but perhaps that is because the VMware virtual server isn't yet on the production server with the appropriate mail server DNS setup). I'm still investigating the forum posts for ideas about that.
Cheers, Tony.