The consensus is that there is no Perl mechanism to get the Ethernet (MAC) address, and there is no built in C library or standard mechanism to pull up this information. Net::SNMP::Interfaces would be nice, but SNMP isn't necessarily running, and I don't have priveledges to start it.

Net::Address::Ethernet module contains OS specific external utility code which I really don't like. However, it does work for Windows, Solaris, Linux, and Mac, so this may be my only solution. There really isn't anything else.