No, these are machines called Power Plate or Noblerex K1. they were designed for astronauts to keep fit in space. It's becoming more common...
The vibrating surface of these devices requires you to recruit muscles for stabilization. Compare standing on solid ground to standing on an unstable surface: The effort to keep your balance is felt throughout your body as you engage muscles to stabilize yourself.
Proponents of these machines claim that the vibrations cause an involuntary reflex muscle contraction - which they do. This makes any workload you place on top of it more challenging. This can be very helpful in a PT setting, which is where I have seen them and had an opportunity to use.
It is unclear from the research, as far as I have been able to find, as to how much benefit translates to the already fit.
Perhaps you've seen this:http://www.nytimes.com/2011/02/15/healt ... ref=health