Elon Musk teases June news on Hyperloop, his rapid transit system for the future

The concept is now fully fleshed out. His idea is a Maglev train which uses ram-air and/or a lifting body to generate lift, and electromagnets for propulsion. It's actually an excellent idea, and I don't see why it wouldn't work. It would be very similar to current dedicated guide way rail systems (similar to Maglev) but much faster and far more efficient, as the electromagnets are used only for propulsion, and the lift is generated via the vehicle's speed.

The biggest challenge would be keeping the vehicle at a constant distance from the power rail, as aerodynamic disturbances (such as turbulent air) would destabilize the vehicle. I assume that his work in rocket control systems would come in handy for this.