patent has surfaced from Sony for a PlayStation 3 controller that is tracked "using hybrid video capture and ultrasonic tracking system." The video capture, according to the patent, will be used to track the horizontal and vertical position (as it would be captured on a two-dimensional image) and the sonar will be used to detect the distance between the controllers, the distance from the controllers to the system and nearby nuclear submarines.
What's interesting to note as well is that the diagrams included in the patent show a pair of nunchuk-style devices for two of the the three shown people, perhaps related to recent rumors of a "break apart" PS3 controller. We'll poke Sony for the usual "no comment," "patents get filed all the time, nothing to see here" and "hey look, a hamster!"
Update: The official statement: "Sony Computer Entertainment files numerous patents globally for the purpose of protecting our inventions. However, it doesn't mean that every patent we file becomes a commercial product. We do not comment on rumors or speculation or comment on each and every patent we file."