A friend of mine just gave me a pair of those way-kewl Nike shoes that include sensors which broadcast your footsteps to your iPod. As Apple and Nike proudly proclaim, their shoes are a revolution in fitness — because they allow an iPod to track precise information about how far you run and how many calories you burn. “Your shoes talk,” as Apple boasts. “Your iPod nano listens.”

And apparently, so does your creepy ex. A group of computer scientists at the University of Washington wondered if they could build a simple device to secretly track somebody by the signal emitted from their shoes. So they set up a laptop, and whaddya know: It turns out that each shoe broadcasts a unique identifier, and it took the scientists only a few hours to write computer code that would sniff it out and track it. They wrote a report summarizing the stalkertastic possibilities raised by the shoes, as their press release reports:

A jealous boyfriend could track a woman’s movements, or compare them with the movements of a suspected rival. And although a receiver only picks up the signal when a person is within range, a stalker could hide receivers near a home, a gym and a restaurant, for example, to closely monitor his or her target’s movements.

Nice! Of course, this is only the tip of the iceberg. As more and more products are shipped with radio-frequency ID labels, it’ll be increasingly easy for people to track where you’re going based on the radio-ID being constantly squirted out by, oh, your cup of coffee.

Speaking of which, you know those new credit cards with “blink” superfast payment technology — where you just wave the card at the cash register and it deducts the money? That’s also RFID technology, and as Boing Boing reported a while ago, those are pretty easy to scan and swipe your information from too. Time to start carrying your credit cards in a radio-proof Altoids tin!