Enabling SNMP in Mac OS X 10.6 (Snow Leopard)

Under Snow Leopard there is a slight change to the way services are enabled.

-w       Overrides the Disabled key and sets it to false. In previous versions, this
         option would modify the configuration file. Now the state of the Disabled key
         is stored elsewhere on-disk.

So, to enable the SNMP daemon correctly:

$ sudo launchctl load -w /System/Library/LaunchDaemons/org.net-snmp.snmpd.plist