Mine had a delivery date of June 24, today, but no iPhone 4 yet. My status changed to "Prepared for shipment" last Monday and it got stuck that way. Today I called Apple twice and got two different answers. First one told me that AT&T has not authorized my order, so I called AT&T and they told me that there was no problem so they re-directed me back to Apple. On the second call, Apple told me that there was nothing wrong with the order but the June 24 delivery date is just an estimate and I will just have to wait until they can catch up with the orders. Go figure.
I pretty much gave up and I don't care anymore if it comes in with the July 2 or July 14 shipments. It's the only way I can keep my sanity. Good luck with yours though.