the old script was very inefficient as it made a call to snmpget for each and every value. Now, it makes one call for each interface to get the name and values, whether in config mode or now.
also, the host name and parameters are now in the plugin-conf.d/munin-node file
Sorry but you did not provide any install instructions. It seems it needs much more than a simple MUNIN installation, as it dies in my case on Ubuntu server 12.04 with: