The 14-day return policy pretty much guarantees that the white iPhone won't become available until at least 14-days after the pre-orders are delivered and there is some sort of general retail availability of the black one.
I assume this is more of Apple's marketing department trying to extend the launch over a month or two rather than a matter of days (they'll get a nice second-launch pop with the white iPhone)... something they've done with great success for the iPad... but whatever, their job is to make their stockholders happy and they do seem to be happy.
30 days for the iPhone.