when someone brought this up to me i looked at it and called it black and blue. i opened the image about 8 times after that, each time in a webpage, and several more times in image editors to pick out individual colors, and then even watched it through a screenshare on someone elses' computer who claimed the dress was white and gold. the image always appeared black and blue to me.
then i went and watched something else for an hour, and completely forgot about this image.
then i checked this thread again. all 15 pages. the dress is white and gold in every single place and i'm just kind of flipping stuff but i also feel like it has to do with the way you interpret the lighting of the image from the first time you see it after a while.
before anyone takes a side and says "this couldn't possibly be this way" take a break, do something else, and just try to think about something else for a while. then come back to the thread next time you're lookin around the forums. keep doing that until the color changes for you, it probably will.