To show off a prototype version of its "Project Glass" augmented-reality eyewear announced last winter, Google required an airship, four wingsuits and parachutes, sign-offs from local and federal government agencie, favorable winds and — not least — reliable mobile broadband.

The craziest stunt I've ever seen at a technology event came about an hour and a half into the keynote opening Google's I/O developer conference at San Francisco's Moscone West conference center Wednesday morning. Google co-founder Sergey Brin barged onstage to interrupt a demo by vice president Vic Gundotra of an Events invitation service for its Google+ social network.

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Brin, wearing his own set of Glasses, said he wanted to show off the eyewear's capabilities but warned that "this could go wrong in about 500 different ways." The video cut to show a zeppelin in the sky. On it, Brin explained, was a friend wearing the same gadget, which functions as a sort of heads-up display by presenting info in a tiny screen positioned above your right eye and can capture and stream photos and videos.

A "no, they wouldn't… yes, they are" moment followed as the screen on the stage switched to a feed from the Google+ "hangout" video chat of not one but four skydivers, and then showed their view as they jumped out over the city.

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Moments later, all landed on the roof of Moscone West, where a cyclist grabbed a package they'd carried, rode down to an edge of the building, and handed it to a climber who rappelled down the side to hand it to yet another biker who sprinted through cheering crowds, into the auditorium, and onto the stage.

A Google rep said the whole idea surfaced in a meeting some six weeks ago. It then required the cooperation of two district offices and the Washington headquarters of the Federal Aviation Administration; the mayor, fire department and police department of San Francisco; and NASA's Ames Research Center in nearby Mountain View.

(Disclosure: I've spoken at a couple of Google events, one paid for by the company.)

Google thinks the demo was the first legal wingsuit skydive in the United States from a rigid-structure airship (that framework distinguishes a zeppelin from a mere blimp). Ian Gregor, a spokesman with the FAA, didn't know if that was the case but said Google complied with the relevant regulations and an authorization specific to the event. He added: "Two FAA safety inspectors observed the jump, and it went off perfectly."

So about the glasses themselves… we'll see. After the demo, Brin announced that a $1,500 "Explorer Edition" would be available for pre-order by U.S.-based I/O attendees for delivery next year.

Glass-wearing representatives staffed a row of desks to take orders but were under orders not to let anybody touch the merchandise. I could look close enough to see the tiny screen hidden inside a clear plastic pod, but I can't tell you if they are, as Google touts, lighter on the nose than many sunglasses.

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It's also unknow how sturdy they will be. Google reps suggested they would allow distraction-free close-up photos of babies, but in my experience babies love pulling eyeglasses off of nearby faces. And battery life apparently needs work too; at a reception Wednesday evening, Gundotra said his prototype glasses don't last as long on a charge as his phone.

But they are a conversation starter, especially when worn while jumping out of a perfectly good airship. A one-minute highlight video is below. If you want the 11-minute version, click here.

Credits: Top photo via Google PR, bottom Rob Pegoraro/Discovery