So my wife and I joined the crowd and got iPhone 3Gs. Now that we have them, we are enjoying them, but it was a pretty big hassle to get them.
I got to the Apple Store pretty early in the morning, and there wasn't a line for iPhones. An Apple Store employees got the two iPhones and started activating the first. The Symbian device lost connection to the service, but after the AT&T Wireless account was created, and after the phone number port started, but before the number was added to the account.
When he got another Symbian device, further attempts to continue the setup kept failing. It looks like Apple's system to register iPhones will only work if the device actually does the registration, and will not work if the phone is configured via the phone with AT&T support. We were on hold with AT&T for over 2 hours, talking to 7 different people at AT&T.
Finally we got the phones registered. What we had to do was add the iPhones to the account with new phone numbers. Then with the AT&T support rep on the phone, the numbers were switched to the numbers that were were attempting to port.
I do appreciate the time that the Apple Store rep spent with settiing this up.
One other problem arose. The microphone on my wife's iPhone didn't work so I took it back to the Apple Store and they did replace it, without too much hassle.