It's an uber-casual form of commuter carpooling. I saw a video the other night, and due to gas prices and congestion in the DC area, folks just line up to jump in a car so that driver can use the carpool lane. Pretty wild.
Hi; just happened to catch your post about slugging. I'm actually working with Zebigo.com, a company based in Seattle that is based on the slugging method of carpooling and we launched last month. People are using for commuting, going to events, and one-way trips. Check us out at http://zebigo.com and let me know your thoughts...we are just getting going, but would love your feedback on ideas on how to make it better!