The white iPhone 4 has officially launched in the U.S. to short lines and constrained supply. One iLounge editor found himself in line outside an Apple retail store this morning with only four or five others, two of which were Apple employees. Notably, this particular Apple Store’s launch supply was quite low, estimated to be only 40 units—somewhat surprising given the long build up to the launch. In addition, white iPhone 4 units are now out on display in Apple’s retail stores, giving potential—or just curious—customers a chance to view the device first-hand.