The documentation seems to be lacking, so here is the list of available
methods:

Functions
Net::Interface::interfaces
Net::Interface::new

Attributes
Net::Interface::name
Net::Interface::metric
Net::Interface::flags
Net::Interface::mtu
Net::Interface::destination
Net::Interface::netmask
Net::Interface::broadcast
Net::Interface::hwaddress
Net::Interface::address

Internal use
Net::Interface::_int_value
Net::Interface::_addr_value

NOTE: Addresses are returned in binary, so to recover a string try:
join(".", unpack("C*", $_->address))

@F = split('', uc(unpack("H*", $_->hwaddress)));
for($i=0;$i<scalar @F;$i+=2){
    $MAC{$name} .= ($i+2<scalar @F ? "$F[$i]$F[$i+1]:" : "$F[$i]$F[$i+1]");
}