With the exception of maybe old Andy Taylor, most police officers in the United States carry a firearm as part of their standard equipment. Wouldn't it be nice to know when those sidearms are drawn, and why? A Silicon Valley startup called Yardarm seems to think so -- it's testing a new gun accessory that can notify police dispatchers when officers draw and fire their weapons. It's a small Bluetooth-enabled sensor that attaches to the officer's pistol and interacts with a companion smartphone. In addition to tracking the gun's action (if it's been fired) and location, it can also sort out which direction the weapon was fired and even if it has simply left its holster.