I've heard it said that you only have to lock your bike better than the one next to it! ;) Personally, I don't ride my road bike when I'll have to leave it alone. It's not replaceable, so I'm paranoid. I reserve my touring bike or my mixte for those type of rides and I keep a cable lock in a bike bag. I have seen many thin lightweight cable locks though, some that you could even put in a jersey pocket. They won't deter a real thief, but they'll keep joyriders and jokers from making off with your bike.
Did anyone else think of the Matrix when you saw that bike tower video? It reminded me of the scene where they show all the humans as 'batteries' in big towers...:p

