So much for trying to port my Verizon mobile number to the iPhone... and actually use my iPhone tonight.
If you've recently purchased an iPhone and want to play with it right away, you may want to postpone porting your number right away. Instead I recommend that you set up a new activation (which only takes about three minutes) and port later.
During the activation process I elected to "transfer my number" from another provider. After providing the previous phone number (easy), billing zip code (easy) and account number (not so easy) I was informed that it would take "up to 6 hours" to complete. I'm four hours past my activation time and still no sign of my email confirmation that my activation is complete.
Although the iTunes FAQ says that you can begin loading and using your iPhone while you wait - it's not true. Your iPhone's a brick while you wait in porting purgatory.
Luckily, I purchased a second iPhone for my wife which she'll promptly receive - after my number port is complete :)
Update: I received an email from AT&T at 7:30 a.m. today (12 hours after my initial activation) stating that my phone number transfer requires 24 hours to complete. This after they initially told me that it would take 6 hours. The email goes on to explain the details:
Phone service is scheduled to be disconnected on your current phone at or after 7:40 PM EDT on June 30. Please check your email and be prepared to reconnect and activate your iPhone before that time. Please call 877-800-xxxx if you'd like to make other arrangements.
Did you also port your number? How long did it take to complete?