Thanks. Good point on the trains, completely missed that.
I guess levitating a live frog seems more interesting to me however. To be able to use magnetics to simulate gravity for humans safely, is IMO, a huge barrier (of many) to space travel/living one day.
My understanding is that they do use such magnets for microgravity experiments. Here is a cool video on diamagnetic levitation from the University of Nottingham: http://www.youtube.com/watch?v=Nod54HFkH0o
The magnetic field used was stronger than the confinement field in ITER - so stronger magnets than you need for nuclear fusion.
We can already levitate much larger things, such as trains.