Never has the color of a dress prompted so much excitement on the Internet. But now, along with some fascinating insights into the science of vision and lessons in overexposure, we have an enduring reminder of the meme, in the shape of an optical illusion truly for the modern age.[XKCD]
For those who *still* don't believe it the person who took the original picture posted a follow up image, it is blue and black just like us sane people were saying all along.
Why some saw it wrong:
Another picture of the dress from the site that sells it (and no, they don't sell a white and gold version).