Hyperloop is a new mode of transport that seeks to change this [transit] paradigm by being both fast and inexpensive for people and goods. Hyperloop is also unique in that it is an open design concept, similar to Linux. Feedback is desired from the community that can help advance the Hyperloop design and bring it from concept to reality. — Tesla Motors
CEO of Tesla Motors, Elon Musk, posted on the Tesla blog his proposal for an alternative to the California High-Speed Rail plan, the Hyperloop. The solar-powered transportation system is proposed to function somewhat like a pneumatic tube, where capsules of up to 28 passengers on air-bearings are transported between Los Angeles and San Francisco in about 30 minutes.
Read Musk's entire proposal here.