Regardless of what Steve said, Apple's official support document notes that you need to have those ports open (or forwarded). I'll go with the documentation, you can go with what Steve said.

That's just stupid. You really think you need to setup a static IP on your phone and then forward ports to it? How would it work if you had multiple phones on the network? It wouldn't. Furthermore, I have several friends that have gotten the phone already, and they were able to FaceTime out of the box in the store and when they got home without any configuration.

Regardless, you can't really argue with the Apple tech note that jonknee linked to - those ports really do need to have port-forwarding enabled for it to work. I'm a big Apple fan, but they still have gotten the firewall-piercing trick down as well as Skype has.

The firewall punching (STUN) works as well as firewall punching works for anyone else. Peer-to-peer between phones won't work if the firewall is setup to block phones, but Skype won't work if the firewall blocks Skype.

A home network and a corporate or military network are much different. Your friends' home network probably has no firewall running on it so all ports are allowed. It's fairly common for corporate networks to whitelist ports and in that case you will need to explicitly open them up or set up forwarding (per Apple's advice).