The answer is very clear.
You can setup Zimbra (both Open Source and Network Edition) on quite a large number of distributions.
As of version 4.0 RC1 (look at the date of this post), if you want to have
support (for your Network Edition), you can only use :
- Red Hat Entreprise Linux ES version 4 (32 or 64 bits)
- Red Hat Entreprise Linux AS version 4 (32 or 64 bit)
- Mac OSŪ X 10.4.7
- SUSE ES 9 (32-bit)
And
no VMWare (nor Xen I guess).
More information is available in the
system requirement PDF.