What does the Day One achievement do?

I was selling some stuff on eBay and noticed people are paying $30-$40 for this Day One achievement code. I have the code, I didn't realize I had it but I looked in my box and found it. I know achievements don't really "do" anything but has MS said if it will unlock anything special in the future?

No, it's just an achievement for buying the XOne on day one. You got the day one controller as well if you bought it day 1. No advantage apart from aesthetics and trophies. EDIT: or the ability to sell it for $30-40.

I like to think we'll get rewarded for having the achievement in the future, I know it's far fetched thinking but hey here's hoping. You should keep it, you got the Day One edition man, flaunt it.

To tell Microsoft that you own the Day one Xbox and then cant download the DirectX12 patch next year. :P.

It just gives you an achievement...nothing special. I'm surprised so many people are willing to purchase that thing for so much.