When I was in Chinatown last weekend, I spotted this in the sky on the way back to the parking lot:
The left-hand side of the message was already illegible. My best guess is that it's advertising a single by Renegade Foxxx called Waydown. (Thanks, Google).
This is the second time I've seen sky writing in Los Angeles. They do love their sky ads - weekends at the beach often have banners being pulled by planes, and blimps get in on the action too.
This sky writing is cool, it's some sort of dot-matrix technology.