#!/usr/bin/env perl                                                                                               

use strict;
use warnings;

my $mac = ( split " ", ( qx(ifconfig en0) )[2] )[1];

print qq($mac\n);

__END__

Karls-Mac-mini:monks karl$ ./endor-moon.pl
2c:07:54:5e:3e:f0 # i faked this, really ;-)