Ah, it seems you're nigh on two years late Phil: High-tech Hitchhiking — Sightline Daily (formerly Tidepool)

Posted Dec. 11, 2006.

So, if someone can figure out how to broker the rental of some of those unused seats, she or he will be rich, and the driver and rider will save money by the oil barrel.

Up to now, the biggest obstacle to such a market has been information. How can drivers and riders find each other? How can they know whether to trust each other? How can they ensure payment?

That’s where the Seattle start-up Goose Networks comes in. Goose has built a real-time ridesharing system that links riders with drivers by combining text-messaging mobile phones, mapping software, a clever database, and a billing system for splitting the cost of fuel.

Some 200 Microsoft employees who live in central Seattle are currently testing the system. Here’s how it works: a goose member sends a text message about her impending departure and location to the central computer, which instantly looks for matches with others going the same way. The service is free for both rider and driver (except for the cost of the text message). Goose’s costs are paid by the employer. (The phone company also makes money on the text messaging. In fact, cell phone companies might do well to underwrite digital hitchhiking just for the texting it generates.)

At some time in the future, Goose Networks believes it can move beyond commute trips, once text-hikers are commonplace and text-hiking is ubiquitous. For now, though, Goose’s whole business plan pivots on employers and commuters. The company aims to grow by adding one large employer after another, capitalizing on the trust among these firms’ employees; their similar commute schedules; and these firms’ obligation under state laws in California, Oregon, and Washington to plan for reduced solo-driving commuters. (Compared to the cost of vanpools, employee transit passes, and showering facilities for cyclists, paying for a corporate Goose program is likely to be a good deal.)

Check the story out for links and more info. Covers all manner of approaches.

I've used a similar service in Thailand, where you flag down the "bus" (converted pickup truck) and tell them where you want to go - if your destination isn't in the opposite direction to the current passengers they will take you right to your destination, altering the route as they go to get the shortest route between all of the destinations.

It was great.