Coming Improvements in Real-Time Traffic data

With both Microsoft & IBM interested in providing content solutions, and dozens of firms competing to present this information to you, traffic information is about to get more timely and more useful.

East Coast's I-95 Gets Real-Time Traffic Reports - TechnoRide:
"The East Coast by summer will have real-time traffic reports, available free, using a sophisticated network of in-vehicle transponders that should in theory - remember, we're talking evolving technology here - be far more accurate than traffic choppers and embedded roadway sensors. It's a joint venture between Inrix Corp., a Microsoft spinoff, and the I-95 Corridor Coalition. Inrix already sells the data that's sent to embedded and portable navigation devices, typically via the Clear Channel radio network. Now it's being provided to the government for redistribution online, via road signs (those useful things that say 'Slow - Congestion Ahead'), and 511 phone services.
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The I-95 Corridor Coalition covers the traffic agencies of 16 states and the initial coverage will be on 2,500 miles of major roads including Interstate 95. Inrix will rely heavily on probe data, meaning two-way transponders in vehicles that also have GPS location sensors. Inrix will also roll up other reports from embedded roadway sensors, traffic cameras, and traditional police / highway department reports, though Inrix believes sensors are costly to install and maintain (especially in frost and pothole regions), so they're going away. Others (not Inrix currently) like cellphone location-sensing for traffic flow information."

Another approach is to turn a lot of cars into nodes in a very large mesh-network. Each car can negotiate with nearby cars for space on the road ("hey I need to get over - make a hole"), and the aggregate of their shared information is the current state of traffic, which can be used to project short-term trends. Consumer products don't care what data collection methods are used because they report information being sold by by the aggregators. For a long time, data will probably come from a variety of sources.

Consumers with privacy concerns can still benefit from the data collected, even if they're not willing to provide data (no transponder, cell turned off, etc.).