Tesla Motors CEO Elon Musk has lobbed yet another teaser on Twitter. For anyone dying to get details on his lightning-fast "Hyperloop" transportation concept, news will be delivered on August 12.

"Will publish Hyperloop alpha design by Aug 12. Critical feedback for improvements would be much appreciated," Musk posted on his Twitter page. Musk also released another detail in response to Ramin Schadlu (@schadlu) about whether this new technology will be proprietary. "I really hate patents unless critical to company survival. Will publish Hyperloop as open source," Musk replied.

Musk first mentioned the Hyperloop a year ago at a PandoDaily event in Santa Monica, CA – what he called a "fifth mode of transportation" following boats, planes, cars and trains. He estimated it would cost about $6 billion to build a San Francisco-to-Los Angeles Hyperloop; that's only about a tenth the cost of a plan that's been floating around the state for years for a proposed high speed rail between the two cities.

More will be revealed on August 12 on what he's called a "cross between a Concorde and a railgun and an air hockey table." It's possible that Musk could announce an alliance with Colorado-based ET3 for its "Evacuated Tube Transport." This transport module would shoot six-person "capsules" through a nearly friction-less tube via magnetic levitation. It would be faster than anything else on earth (though not as fast as the SpaceX Dragon in outer space) – 4,000 miles per hour. Hyperloop travelers would make it from New York to LA in less than an hour.