Hymnson - think of it this way.
If Dean Kamen got on Good Morning America yesterday morning, and rather than revealing the Segway, revealed grand plans and sketches of a Utopian city - everyone would have thought him nuts.
Nothing has ever really come from master plans for perfect cities. Ever.
But, instead, Dean offers us the Segway HT, an emissionless, small, efficient transport device. It has the benefit of being faster than a walking pedestrian, but safer than a moving vehicle. As such, no special, expensive, complicated infrastructure is necessary (The big dig, anyone?)
So, what happens is people begin to use the Segway HT on their own - and then, as time passes, there's a much greater demand for urban planners to work the technology into their plans. As time progresses, when downtown, urban areas are reworked, we'll see them move entirely away from the automobile as a viable method of transportation.
So, like Colleen said, those streets are made into parks and plazas, with widened areas for pedestrian, and Segway use.
It's a grass roots campaign to change the world. Dean realized that nobody would take him seriously if he set out to design the automobile out of cities. But, by developing the technology that can allow that to happen, he's setting into motion the events that'll make the general public demand the automobile out of cities.
We can ignore one man and call him crazy, but we can't ignore an entire culture
Clever, if you really think about it.