Seen here "Together at last? Bike lights and a cable lock":
"... combines a headlight and tail light with a 6-foot (1.8-m) coiled steel cable lock."
The two lights are permanently attached to either end of the 9-mm-thick cable, and sit on quick-release mounts on the handlebar and seatpost when the bike is in motion. When it's time to lock up, they come off, and a sliding steel barrel lock on the cable is used to secure it around an adjacent immovable object such as a lamp post or railing.
Both lights are IPX6 water-resistant (they stand up to heavy splashing and rain) and are electrically-linked by the cable, with one charge of the single lithium-ion battery being good for seven hours in steady mode or 14 when blinking. The headlight kicks out 200 lumens, while the tail light is rated at 30.
On Kickstarter site:
$4,524 pledged of $39,000 goal
20 days to go