One thing the dress-color disagreement does make clear: color, like beauty, is not in the object but in the beholder—specifically, color (and beauty) are an experience belonging to the beholder. We often try to place attributes totally in the object when in fact they are experiences in the subject: “Does fried liver have a good taste?” (or “Does cilantro have a good taste?”) reads as though the taste is in the object, but quite clearly it is not: the same object (fried liver or cilantro) can taste very good indeed and quite foul to others, with the object unchanged.
So when we talk about the color “of the dress,” we are really talking about subjective experiences, which naturally enough vary as the subject varies.
But New Scientist has an explanation that may be of interest.
Brian By Experience 