Wal-Mart, on the other hand, is a whole other, evil can of worms. Sure, it's great for inventorying, as gregortroll has noted (two seperate posts linked, there). But the chips are never deactivated...which means that a Wal-Mart marketing drone could conceivably drive by your house, hit a button, and learn just how many of their products you've purchased. THAT's invasion of privacy...on a really severe and scary level.
While I'm on the topic of the EFF, I'd just like to note that they're an incredible organization doing tremendous work to keep electronic privacy and rights sane. They're working on a wide variety of issues, including the fair use of copyright law, peer-to-peer file sharing, voting machines, and some of the more direly privacy invading specifics of the Homeland Security folks. Please try to support them in any way you can. Sign up for (and participate in) their action alerts, support their supporters, or if your holiday budget allows, send them a donation or join. They're doing incredibly important work.