In previous releases of ESXi, only SNMP v1 and v2c was supported on the host. With the latest release of ESXi 5.1, we now have added support for SNMPv3 which provides additional security when collecting data from the ESXi host. You also have the ability to specify where to source hardware alerts using either IPMI sensors (as used by previous release of ESXi) or CIM indicators. You can also filter out specific traps you do not wish to send to your SNMP management server.
In addition to SNMPv3 support, we also now have an ESXCLI equivalent command to the old vicfg-snmp command. This means that you no longer have to use multiple commands to configure your ESXI hosts and can standardize on just using ESXCLI for all your host level configurations.