If you have AirPort on both, you don't need the cable. You can connect the two via the AirPort card in a wireless network. I get faster transfer speeds via AirPort then I do with an ethernet cable.
You won't get Internet access between the two while you're in a network, but for file transfer, it's easy. You don't even need to reboot.
Have file sharing on, go to your AirPort and create network. Then all you have to do is join up.