Please people, can't you just wait to pre-order tomorrow? Or the next day? They aren't going to sell out in the first couple of days of pre-orders. I doubt you will get the phone any earlier based on when you pre-order or at least not any difference between the first couple of days of preorder.
One thing to clarify for a few readers, because I see this confusion about when you get charged for a pre-order a lot. If you use a debit card, you will be charged immediately because the seller needs to check that you have the cash in your bank account at the time of the transaction. That money gets frozen in your bank account immediately. A credit card should only be charged when the product ships (the seller knows that Visa or Amex is going to have the cash then, so they can wait).
Finally, if Apple can have this kind of response on preorder days, this means that iPhone 4 is going to be a huge hit. I'm thinking that it will outsell every Android Phone easily, outsell every individual Android Phone manufacturer, and come close to selling as many as all the Android Phone's together. I'm going to get one through work once work has approved them. They just recently approved the iPhone in general, so I hope that it doesn't take too long to approve a new model.