Here is the upgrade output

zimbra:~/zcs# ./install.sh

Operations logged to /tmp/install.log.20353
Checking for existing installation...
zimbra-ldap...FOUND zimbra-ldap-3.1.4_GA_518.DEBIAN3.1
zimbra-logger...FOUND zimbra-logger-3.1.4_GA_518.DEBIAN3.1
zimbra-mta...FOUND zimbra-mta-3.1.4_GA_518.DEBIAN3.1
zimbra-snmp...FOUND zimbra-snmp-3.1.4_GA_518.DEBIAN3.1
zimbra-store...FOUND zimbra-store-3.1.4_GA_518.DEBIAN3.1
zimbra-apache...FOUND zimbra-apache-3.1.4_GA_518.DEBIAN3.1
zimbra-spell...FOUND zimbra-spell-3.1.4_GA_518.DEBIAN3.1
zimbra-core...FOUND zimbra-core-3.1.4_GA_518.DEBIAN3.1
./install.sh: line 1: rpm: command not found

Saving existing configuration file to /opt/zimbra/.saveconfig


PLEASE READ THIS AGREEMENT CAREFULLY BEFORE USING THE SOFTWARE.
ZIMBRA, INC. ("ZIMBRA") WILL ONLY LICENSE THIS SOFTWARE TO YOU IF YOU
FIRST ACCEPT THE TERMS OF THIS AGREEMENT. BY DOWNLOADING OR INSTALLING
THE SOFTWARE, OR USING THE PRODUCT, YOU ARE CONSENTING TO BE BOUND BY
THIS AGREEMENT. IF YOU DO NOT AGREE TO ALL OF THE TERMS OF THIS
AGREEMENT, THEN DO NOT DOWNLOAD, INSTALL OR USE THE PRODUCT.

License Terms for the Zimbra Collaboration Suite:
http://www.zimbra.com/license/collab...cense_1.0.html


Press Return to continue

Checking for prerequisites...
NPTL...FOUND
sudo...FOUND sudo-1.6.8p7-1.4
libidn11...FOUND libidn11-0.5.13-1.0
curl...FOUND curl-7.13.2-2sarge5
fetchmail...FOUND fetchmail-6.2.5-12sarge4
libgmp3...FOUND libgmp3-4.1.4-6
libxml2...FOUND libxml2-2.6.16-7
libstdc++6...FOUND libstdc++6-3.4.3-13
openssl...FOUND openssl-0.9.7e-3sarge1

Checking for installable packages

Found zimbra-core
Found zimbra-ldap
Found zimbra-logger
Found zimbra-mta
Found zimbra-snmp
Found zimbra-store
Found zimbra-apache
Found zimbra-spell


The Zimbra Collaboration Suite appears already to be installed.
It can be upgraded with no effect on existing accounts,
or the current installation can be completely removed prior
to installation for a clean install.

Do you wish to upgrade? [Y] Y

Select the packages to install
Upgrading zimbra-core
Upgrading zimbra-ldap
Upgrading zimbra-logger
Upgrading zimbra-mta
Upgrading zimbra-snmp
Upgrading zimbra-store
Upgrading zimbra-apache
Upgrading zimbra-spell

Installing:
zimbra-core
zimbra-ldap
zimbra-logger
zimbra-mta
zimbra-snmp
zimbra-store
zimbra-apache
zimbra-spell

The system will be modified. Continue? [N] Y

Shutting down zimbra mail

Backing up ldap


Removing existing packages

zimbra-ldap...done
zimbra-logger...done
zimbra-mta...done
zimbra-snmp...done
zimbra-store...done
zimbra-spell...done
zimbra-apache...done
zimbra-core...done

Removing deployed webapp directories
Installing packages

zimbra-core......zimbra-core_4.0.0_GA_303.DEBIAN3.1_i386.deb...done
zimbra-ldap......zimbra-ldap_4.0.0_GA_303.DEBIAN3.1_i386.deb...done
zimbra-logger......zimbra-logger_4.0.0_GA_303.DEBIAN3.1_i386.deb...done
zimbra-mta......zimbra-mta_4.0.0_GA_303.DEBIAN3.1_i386.deb...done
zimbra-snmp......zimbra-snmp_4.0.0_GA_303.DEBIAN3.1_i386.deb...done
zimbra-store......zimbra-store_4.0.0_GA_303.DEBIAN3.1_i386.deb...done
zimbra-apache......zimbra-apache_4.0.0_GA_303.DEBIAN3.1_i386.deb...done
zimbra-spell......zimbra-spell_4.0.0_GA_303.DEBIAN3.1_i386.deb...done

Setting defaults from saved config in /opt/zimbra/.saveconfig/config.save
HOSTNAME=zimbra.interlix.org
LDAPHOST=
LDAPPORT=
SNMPTRAPHOST=zimbra.interlix.org
SMTPSOURCE=admin@interlix.org
SMTPDEST=admin@interlix.org
SNMPNOTIFY=yes
SMTPNOTIFY=yes
LDAPROOTPW=<hidden>
LDAPZIMBRAPW=<hidden>
Restoring existing configuration file from /opt/zimbra/.saveconfig/config.save...done
Operations logged to /tmp/zmsetup.log.23490
Setting defaults...Setting defaults from existing config...Done
Upgrading from 3.1.4_GA_518 to 4.0.0_GA_303
Thu Aug 31 22:15:29 2006: Stopping zimbra services
Thu Aug 31 22:15:34 2006: Checking mysql status
Thu Aug 31 22:15:34 2006: Starting mysql
Thu Aug 31 22:15:35 2006: SELECT value FROM config WHERE name = 'db.version'
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/opt/zimbra/db/mysql.sock' (2)
Error while running '/opt/zimbra/bin/mysql --user=zimbra --password=<hidden> --database=zimbra --batch --skip-column-names'. at /opt/zimbra/libexec/scripts/Migrate.pm line 134.
zimbra:~/zcs#

----
Mysql is in fact running. and /opt/zimbra/db/mysql.sock is there.

What should I do next?