George Costanza, who never pays for a garage, fights for on-street parking on Seinfeld.

In subtle but potentially significant ways, the Web is changing the way we as urban residents relate to the automobile. Zipcar allows you to rent a nearby car by the hour without visiting a counter — a method of car sharing that could drastically reduce the need for parking spaces in urban neighborhoods. Platewire allows people to flag license plates of rude, antisocial or dangerous behavior of errant motorists. And now comes a website with an idea that, um, may be a blessing or a curse for those of us who value livable streets: SpotScout.

If ever there was a sign that Donald Shoup’s assertion that curbside parking is too cheap for the city’s own good, this is it.

SpotScout will allow a motorist to buy from another motorist information about when he or she is leaving a free or nominally priced curbside space. The price one pays for this information will supposedly be set by market forces: Spaces in busy areas would be worth more as drivers bid up the cost of information about these spaces. Spaces that are free would presumably be worth more, too. Transmitted via a cell phone or other mobile device, this is supposed to operate in real time.

To those who might object to the idea that a private individual is receiving gain for a public parking spot, the website includes this important clarification:

On-street spaces cannot be reserved under any circumstance. Information pertaining to another individual’s departure time may be traded and/or purchased.  Purchase of departure information does not allow, or transfer any rights to a space.  Furthermore, an individual purchasing said information is not empowered with any additional rights over other parties wishing to occupy that space.

So just to be totally clear: it isn’t as if one is paying for the space. One is simply paying for information. If this service were to catch on, the implication would be clear: If people are willing to pay, say, $5 for access to a free on-street space, then that’s how much money the city, i.e., the public, would be losing by not charging for it. Bit by bit, Shoup and ideas like this are chipping away at the previously unassailable notion that on-street spaces should be free or nearly so.

As for how this website might play out in the streets, I think there are potential benefits and problems. It would hopefully eliminate the proportion of congestion that consists of people driving around looking for free on-street parking spaces. But if multiple people learn of the same spot at the same time (either through the website or via the old-fashioned method), it could lead to arguments or worse between motorists who may feel that they are being cheated out of something they bought and paid for.

I was optimistic about this idea at first, but then I ran it by my friend Gary Roth, the author of An Investigation Into Rational Pricing for Curbside Parking. He was, to put it mildly, skeptical. "This is an awful idea," he wrote in an e-mail. "People selling something they don’t own? Selling something they don’t have the right or permission to hold for someone else?"