Yeah. They use them a lot in NY NY. If you know a mechanic or have a contact with a mechanic supplies co. then you can (with a little bit of venture capital) rent some space set up a few of these babies then have a full ROI(Return On Investment) and then some in a couple months! With parking being soo scarce and this being a get-rich-quick scheme it's rather popular in large cities (esp in Japan).
How do they get them down? It's basically a car lift used in the auto shop. They would drive the one car underneath out and into a clear spot (they usually have 'staging' spots set up where they stage the cars to be put up onto the lift) then lower the lift and then replace the car taken down with the one in staging. I first saw these in New York, NY USA.