Elon Musk has posted details of his Hyperloop mass transportation system concept :

• Hyperloop | Blog | Tesla Motors
• Hyperloop | SpaceX
• Hyperloop-Alpha.pdf – writeup starting witha general overview and then followed by a technical analysis.
• Revealed: Elon Musk Explains the Hyperloop – Businessweek
• Hyperloop Physics 101 With Elon Musk – Businessweek

Seems like a clever approach. More practical than the air-tube or vacuum tube concepts that have been around forever.

Elon recently said he would turn the idea over for open source style development and reserve his time for SpaceX and Tesla Motors.

I hope someone or group can push it to a hardware test level. As with innovative concepts for rockets, the upfront costs for such systems are so high, it is very difficult to get through development problems and setbacks without running out of money.