Email a copy of "3G iPhone Preference Found in Beta 5 Firmware" to a friend.
It is in the beta 5 .ipsw, but will normally not show up on an EDGE iPhone. Turning 3G on will just crash the phone if you use an EDGE phone. If you do not believe me, then decrypt the beta5 rootfs dmg, and see for yourself in /Applications/Preferences.app/Network.plist
