To be honest, I do not think Apple is that worried about people returning it for the white. As Steve Jobs has stated, the raw data has shown that basically a microscopic amount of people are unhappy and have already returned their phones. People who have wanted the white iPhone 4, for the most part, either waited or have since purchased the black iPhone 4 and are happy with their purchases. Don't let a forum influence your perception of customer's preference, as we already know that Steve Jobs does not and it is way less than 1% of the iPhone owners. We both know that Apple loves to launch products on Thursday-Saturdays. With that being said, I believe we might be seeing this phone online and in store sooner than we know it, my prediction being the 23rd or 24th.
And also a long those lines, I think it has already been implied the hardware bears no difference between the black and white units. Hence, all iPhone 4s purchased through the end of September are accompanied with a free bumper or an equivalent case that Apple will offer either tomorrow or Friday (my guess being 4am tonight).
I don't think the returns Steve cited has anything to do with those looking to return black for white. Those are people who are discontent with the phone as a whole, not because of color.
The limited quantities of the White iPhone make any number of those looking to exchange a significant number.
To several posters above:
Can we NOT have the black/white exchange ethics discussion? We've had it 3 times already. It's ugly and rather depressing. This is the 1st White iPhone thread in a while that hasn't been dragged down by that topic.
Some math:
.5% of 3 million is 15,000 which would be 15% of the estimated 100,000 iPhones. A rather significant number if you ask me.