Surprise! iPhone 4s hit earlier than even Apple expected
The question is, why? Apple has never wanted customers to receive delivered iPhones before stores starting selling them. There's an obvious possibility, and it points to Apple's BFF ...
The reason that that comes to mind is that Apple wants to prevent a repeat of last week's AT&T server meltdown: Apple is trying to spread out activations to prevent another SNAFU. In the past (once again) customers have experienced activation issues on launch day, as the servers simply couldn't handle it. Even given this step, there is a decent probability the same will happen aqain. Every time a new iPhone launches, there are inevitable delays for some activating phones.
The emails that Apple sent said that those receiving the email would definitely receive the devices on June 23rd, even if their FedEx tracking info showed a later date. In the past, Apple has had FedEx hold the package until the day of retail launch. Ah, but with the handcuffs off, some saw devices delivered on the 22nd!
Electronista reported they received an iPhone 4, but also received an activation failure on their side, saying that AT&T's servers don't appear ready for activations on the 22nd. However, a MacRumors user has successfully activated, so perhaps that's just a spurious issue on Electronista's part. In fact, that's his iPhone 4 above.
At any rate, many more will received their iPhone 4s today, including us. If you see activation delays, keep trying: that's about all you can do.