If you're wondering what the deal is with the posting of a color in Facebook, it's a meme to promote breast cancer research. This Salon article discusses it. The woman posting a color is supposed to be posting the color of the bra she happens to be wearing at that time. Yeah, that's it. So you see the connection between "white" and breast cancer research? Neither do I.
I thought about doing it, but decided against it because I didn't see the point of simply posting a color when you don't know what the heck was going on. How would you know that this is supposed to be about promoting breast cancer research if all they do is post a color?
I only posted "White" above because that is the color of almost all my bras (comes with wearing a white costume, after all!), so what would be the point of simply posting "white" every day? If you didn't know about the breast cancer meme, you might think that I was promoting racism!
Anyway, now you know. :-)