It seems that changing the color of a phone is a lot more harrowing and complicated process than any of us could possibly realize. After Steve Jobs originally stated that the white iPhone 4 would be available by the end of July at the "Antennagate" conference last week, now Apple is stating that problems are cropping up again and it won't be available until "later this year."
The full statement from Apple: (via TechCrunch)
White models of Apple's new iPhone® 4 have continued to be more challenging to manufacture than we originally expected, and as a result they will not be available until later this year. The availability of the more popular iPhone 4 black models is not affected.