Hi,
this object is called dot1dTpFdbAddress, and you're correct: The return value is a MAC address. This MAC address is also the last part of the OID on the left side of the equal sign, in decimal.
I haven't worked with the perl module so far but net-snmp allows you to change the output options:
snmpbulkwalk -v2c -c public -OQs 192.168.1.23 1.3.6.1.2.1.17.4.3.1.1
mib-2.17.4.3.1.1.156.78.32.64.192.120 = "9C 4E 20 40 C0 78 "
snmpbulkwalk -v2c -c public -OQas 192.168.1.23 1.3.6.1.2.1.17.4.3.1.1
mib-2.17.4.3.1.1.156.78.32.64.192.120 = ".N @.x" (ASCII)
You can find more information about the output options of your implementation in the man pages (man snmpcmd) or here: http://www.net-snmp.org/docs/man/snmpcmd.html
HTH
Rolf