SAN FRANCISCO -- Hard to believe, but there was once a time when the visionaries worked for the government. Rebuilding a ruined Europe, putting a man on the moon, ending poverty, connecting the American interior with highways -- these were immense tasks undertaken, and often achieved, by bureaucrats.

The wild dreamers these days work for technology companies. Elon Musk, not content with making the first commercially viable electric car, has plans for a trainlike system that would speed travelers at 600 mph. Google, hard at work assembling the world's information, has started a company to cheat death. Mark Zuckerberg has plans to put everyone in the world in touch.

And now Jeff Bezos, Amazon.com's chief executive, says he is planning to take something that looks like a barbecue grill, attach eight propellers and a basket to it and use it to deliver small items to people's houses. He sketched a vision where no one would ever have to get off their hammocks to get a resupply of Pringles or Milk Duds.

Package delivery by drone is a loopy idea, far-fetched and the subject of instant mockery on Twitter -- but it is hard to deny its audacity.

"I am blown away by what I see coming out of the private sector these days," said Andrew McAfee, co-founder of the Initiative on the Digital Economy at the MIT Sloan School of Management. "All the building blocks are in place for breakthroughs: The Internet goes everywhere. Everyone has a device connected to the network. And the cost of technology experimentation is so low. We don't need one single entity with massive resources to deliver these really cool innovations."

The announcement by Bezos on Sunday evening was one of those moments when the future suddenly seems much closer. But the news also served to emphasize a less appreciated hallmark of the tech world: its masterful use of public relations.

The revelation came at the end of a "60 Minutes" feature about Amazon and its preparations for Cyber Monday, the year's most hyped online shopping day.

"We can do half-hour delivery," Bezos said. He also said the drones could carry as much as 5 pounds and could fly 10 miles from the delivery center.

"I don't want anybody to think this is just around the corner," he said in an uncharacteristic note of caution.

Which brought up the immediate question: Why announce it now? Amazon is so tight-lipped, it will not often confirm what happened in the past, like how many Kindles it has sold. It almost never talks about the future.

On the show, Bezos dodged a question about whether Amazon would soon unveil a set-top box. "I don't want to talk about the future road map of our devices," he said.

Unless, apparently, he did want to.

"Whether this ever amounts to anything, it was definitely a good PR move," said Tory Patrick, leader of the retail technology practice at Walker Sands, a consultancy. "It's Cyber Monday and Amazon is on the brain."

An Amazon Web page unveiled immediately after the "60 Minutes" broadcast was much more bold about the drone delivery service, which is called Prime Air. "We'll be ready to enter commercial operations as soon as the necessary regulations are in place," Amazon promised.

That, it said, meant 2015, when the Federal Aviation Administration will issue new rules for commercial drones. The FAA needed a year merely to prepare its 74-page plan for the integration of drones into the national airspace. Specific details on putting those rules into effect, the agency said when it released the plan last month, are still to come.

Sen. Edward Markey, D-Mass., a member of the Commerce, Science and Transportation Committee, said he was dissatisfied with the FAA plan because he felt it had scant privacy protections.

"Clear rules must be set that protect the privacy and safety of the public," he said in a statement Monday.

Jaron Lanier, a technology skeptic who wrote "You Are Not a Gadget," said the drones would encourage the sort of divisions that undermine society.

"I can easily picture a scenario where drones deliver things to upscale tech-savvy customers," he said. "But note the implication, whether intended or not, that working-class truck drivers will no longer transgress geographic class lines.

"It's also hard to imagine delivery drones flying unmolested in restive working class or poor areas. They'd become skeet or be 'occupied,' depending on the nature of the neighborhood."

McAfee, co-author of "The Second Machine Age: Work, Progress and Prosperity in a Time of Brilliant Technologies," said he saw more benefits. "Amazon drives a big truck to the outskirts of town, unloads the drones, and they go run a bunch of final drops," he said. "The roads will be less crowded. You'll have less pollution."

Patrick, the consultant, said there was no question of what people will want.

"If Amazon can pull this off, people will say, 'This is awesome, I can get toilet paper in 30 minutes.' And they will."