Yes I know that you cannot pre-order white iPhones, but that does not mean they wont have them at launch. I went to my local apple store today and the guy told me that just because you cant pre-order doesn't mean they wont be available at launch *wink*, he also told me that if i pre-order a black one and they have white ones in stock at they can give me a white one instead. Now lets talk about why apple would decide not to do pre-orders on the white iPhone 4.
6. We know white iPhones exist, we saw them at WWDC. They might as well sell what they've got because the demand is probably going to outstrip supply and there is no point in sitting on a stash of white iPhones just because they dont have enough for everyone, that doesnt make any sense. They will sell every last iPhone they can.