Researchers asked 104 volunteers to walk across boards studded with thousands of highly sensitive pressure sensors. They recorded 10 steps per person and then analysed how each persons step changed to produce a unique profile for each person.File this one under "Any biometric modality can be useful, especially if it’s the only one available."
It is, however, extremely unlikely that the footstep biometric described in the story will ever be the only one available. If you can put a ten foot electronic carpet somewhere, you can probably put a camera or fingerprint reader there, too. Then there's the enrollment process.
This does serve to show that nearly anything (and I mean anything) could theoretically be used as a biometric identifyer, but I wouldn't want to clean the sensor.