Here's a nice surprise for early adopters who managed to successfully place an an iPhone 4 preorder on the first day it was possible to do so: at least some of you may receive your device a day early.
Here is Apple's e-mail:
Dear Apple Store Customer,
You recently received a Shipment Notification email from Apple advising you that your iPhone has shipped.
This email is to confirm that your delivery will occur on June 23rd. Although Apple and FedEx tracking information may currently indicate a later date, you can check the FedEx website the morning of the June 23rd to track your package to your doorstep.
In the event that you will not be available to accept delivery on June 23rd, it may be more convenient to use our pre-sign delivery option by visiting our Order Status website at http://www.apple.com/orderstatus.
The Apple Store Team
The reason for the change in delivery date isn't clear though it might be that the company is hoping to protect its servers from meltdown by staggering initial iPhone activations over two days.