The Hyperloop has been vaguely described by Musk as a "cross between a Concorde, a rail gun, and an air hockey table." A better description might be an elevated tube system with a magnetic levitation system similar to high-speed bullet trains. The kicker would be the enclosed tube, which would provide a nearly friction-less surface for individual capsules to travel in.
ET3 has already built mock-ups and prototypes and is planning a 3-mile test run by the end of 2013.