So first of all, let me recommend SCOTUSBlog and the actual court decision rather than the Atlantic:
http://www.scotusblog.com/?p=143279 http://www.scotusblog.com/case-files/cases/kirtsaeng-v-john-...
Now what's going on here: Congress said (1) you have a right to resell copies of copyrighted work "lawfully made under this Title", but (2) you can't import copyrighted work from other countries without the copyright holder's permission. This is intended to make it possible to sell things at different prices in Mexico City and LA, which in turn makes it more viable to sell things in Mexico City at all. You may not love it, but it's at least a rational system.
The Ninth Circuit has interpreted this, using common sense, to mean that if a publisher voluntarily imports stuff and sells it in LA, and then you buy it and resell it, the doctrine of first sale applies. What happened in this case is someone was straight up running a business importing and reselling stuff that wasn't intended for the United States. But instead of focusing on that, the Second Circuit took a closer look and said, waitaminute, these books aren't "lawfully made under this Title" in the first place, because they were made under someone else's statutes instead of ours. So whether or not you had the right to import them, you don't have the right to resell them.
Now, as the defendant and the dissent and the Ninth Circuit have all pointed out, that's nuts. It destroys the doctrine of first sale for everything manufactured outside the United States, which makes no damn sense in anyone's world and isn't even necessary to stop what Congress actually wanted to stop. Maybe this is optimistic, but I really don't think there's going to be anyone who manages to get behind that as a Good Thing. So I'm not planning to panic until (1) the Supreme Court fails to salvage this one, and (2) Congress fails to immediately patch up whatever mistake they built into the statute.
Side note: the Atlantic tries to make this a little more dramatic with "Almost every product made now has a copyright logo on it. That logo, alone, empowers manufacturers to sue people for copyright infringement for unlawful sales." There's some truth hidden in there, but it's a really weird way to put it. It is indeed possible to get copyrights on design elements of products, but only if the design elements are totally separable from the actual purpose of the product -- basically if the stuff you claim copyright on could be fully removed from the product and it would still work exactly as well.[1] So can you really copyright an iPad? I'm skeptical -- what's the element of the design that isn't functional? If they're saying that the Apple logo itself is the copyrightable design element, I have trouble buying that -- an iPad isn't the same as, say, a watch with an Apple logo for a face. I think this aspect of their concern is dramatically overstated. (Trade dress, the basis of the Apple v. Samsung cage match, is a different issue, but not one that's relevant to resale.)
TL;DR: WTF with a side of Don't Panic.
[1] Random explanation of design copyrights: http://www.jdsupra.com/post/documentViewer.aspx?fid=d1f71ed3...