If Zabbix is logging to syslog then after an upgrade to Zabbix 2.0.11 you will see changes in the application names appearing in syslog:
Zabbix agent → zabbix_agent
Zabbix Agent → zabbix_agentd
Zabbix proxy → zabbix_proxy
Zabbix server → zabbix_server
Zabbix get → zabbix_get
Zabbix Sender → zabbix_sender
The old, incorrect names (on the left) contained a space which is not allowed by RFC 5424 for APP-NAME. If you are using regular expressions in monitoring of syslog you may want to adjust them for the new application names.