Raise your arm before a turn, and a tilt switch activates big amber LEDs to signal your turn at night. An accelerometer detects when you slow down to illuminate a big patch of red LEDs on your back. This clever cyclist jacket is the invention of Michael Chen in London, who won a design competition with this jacket. He hopes a manufacturer will pick up his idea in time to make the jacket available in time for Christmas for UK£100 (about US$200). This cyclist jacket is demonstrated in the video below.
Hat tip to Cycle Dog, who wonders how the wiring and electronics will hold up under constant use and wet weather riding.