Ashlee Vance spoke to Musk about his Hyperloop idea:
As for safety? Musk has heard of it. “There’s an emergency brake,” he says. “Generally, though, the safe distance between the pods would be about 5 miles, so you could have about 70 pods between Los Angeles and San Francisco that leave every 30 seconds. It’s like getting a ride on Space Mountain at Disneyland.” Musk imagines that riding on the Hyperloop would be quite pleasant. “It would have less lateral acceleration—which is what tends to make people feel motion sick—than a subway ride, as the pod banks against the tube like an airplane,” he says. “Unlike an airplane, it is not subject to turbulence, so there are no sudden movements. It would feel supersmooth.”
The hot thing amongst pundits at the moment seems to be to snark this to no end and mention it in the same breath as things like the Segway. But I unequivocally love everything about this. I want to live in a world where this exists. I really hope someone builds it.