Over at Slashdot, former International Space Station director Mark Uhran talked about whether the amazing space habitat we saw in Elysium is realistic. It turns out the biggest problem isn't what you'd expect.
The space habitat in Elysium is rotating around a central axis, which likely creates enough centrifugal force in the torus to prevent the kind of muscular and skeletal damage that astronauts suffer in zero gravity. So that's slightly realistic. The real problem is the radiation shielding: