I had not heard about this until the Morning Mashup was talking about it on the radio this morning and then thankfully gE is here to explain it to me...
The dress is clearly blue and black. That original post ITT looks washed out causing it to be periwinkle and faded black. Even the angles or whatever that people are seeing as gold/white, still just looks like blue/black just more washed out to me. (I can see how some people might perceive it as gold but those people would be wrong.)
Also, I have proven to have excellent color perception by taking several online colorblindness tests and comparing my results to other people in my office.