Uber app in action.
Uber app in action. - 
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According to AllThingsD's analysis of public filings and sources, on-demand car service Uber has a value of $3.5 billion.

"It's reflective of just how quickly this has caught on in this idea of using new technology to disrupt existing industry," says AllThingsD senior editor Ina Fried. "If we look out a little bit at the future of transportation, really, cars should be an on-demand service for all. Not just the occasional taxi, but also just when you need a car. You don't need a SUV most of the time, but there are times that you do. That car should be available on-demand, this could be a bet on a future far bigger hailing a taxi or getting a towncar."

While Uber is in a good position to change the future of transportation, its stand-offs against regulators might have more impact than where technology goes.

Battles against the city of Los Angeles and elsewhere makes the future murky.

"How should services like Uber be regulated? Should they be regulated like a taxi? Should they follow the same rules?" asks Fried. "There's another service that lets you rent a car that someone else is going to park at the airport, and they're getting competition from rental car companies. A lot of these [new transportation systems] have open questions of how they should be treated."

Follow Kai Ryssdal at @kairyssdal