I just spoke to CPW Internet Sales Support, as mine is still in Stage 2, for delivery today(!)
I asked him if there is categorically an iPhone with my name on it in their warehouse. He said yes, definitely, but the guys in the warehouse are just having a lot of trouble getting them out the door.
I mentioned that there are reports that CPW have oversold their stock and now are unable to fulfil existing orders which is why I was asking.
He said that they do have unsold iPhones in stock, but they're waiting to clear the backlog so they can figure out exactly what they've got left, and then they'll reopen sales. He said that they stopped processing orders around 2-3pm yesterday... I'm not sure what that exactly means.
So, Monday for me, if I take his word for it.
I have had essentially the same problem: still in stage 2 (although with status message saying that it "should have arrived" today!).
The CPW guy I spoke to could not have been more helpful and honest. (Sounds like he and his colleagues have been getting rather a lot of abuse, which is rather sad, given that this is only a 'phone we're talking about.) The explanation I got is that the warehouse is simply swamped, consistent with gid's post, above, but that there is an iPhone assigned to me, which will be delivered on Monday or Tuesday.
So if that's what happens, I'll be quite satisfied. It's certainly not going to kill me if I don't get my new toy for another two or three days - and, more importantly, I can now take my daughter to the bookshop instead of waiting in for the delivery today!