A tale of 5 phones
I am on an AT&T family plan with four lines, so the whole house was excited today. My 4S arrived around 10:30 am, and I promptly tried to activate it. I got that message telling to wait for an email. I waited for hours, meanwhile backing up and cleaning out everyone's phones. Finally I decided, screw that, I'll just use the SIM from my 4. I was already planning to transfer the 3GS line to the 4 and putting the SIM from a Pantech flip phone into the 3GS, but the SIM from the 3GS won't fit in the 4, so I decided to just take all the phones to the Apple store. When I bought my 4 there last year, they were able to transfer from 3GS to 4, but this time they told me I'd have to go to AT&T. However, I did swap all the other SIMs right there, and the 4S was activated.
There were two lines at the AT&T store, one to buy phones and one for service. I waited in the service line, during which the lady next to me dropped her new 4S on the sidewalk and broke the glass back! Finally, I got a new SIM in the 4. However, they could not get through to the server to activate the new SIM, but said it would do so on its own, and a little while later I tried rebooting it and the "No SIM" turned into "AT&T 3G".
So, the line on the 4 went in the 4S, the line on the 3GS went in the 4, an the line on the Pantechwent in the 3GS. I restored the 4 and 4S from backups, and set the 3GS up as a new phone. I had three working iPhones. After it was all done, the fourth phone owner announced that he wanted to take the SIM out of his Cingular Nokia flip phone and put it in the now empty Pantech, which is only 6 months old.
So that's three iPhones, four people and five phones total. (6 if you count the broken one.)