Or more precisely, a Family Pack is a single disk with permission to install it on 5 machines at the same residential address, or machines belonging to students whose primary home is at that address. Not for 5 friends at different addresses to share.
I find it amazing that people actually think that Apple will continue to offer specially discounted Family Packs if people abuse them by ignoring the terms of the EULA. A appreciate that I can buy a Family Pack for my 2 home machines, and it costs less than buying a separate copy for each machine.
If Apple intended the Family Pack to be used as a discounted 5-user multi-address pack, it would price it at $499 instead of $199.
We have a good thing going here with the Family Pack - let's not ruin it for ourselves!