In English-speaking physics classes, this is usually called the "Tennis Racket Theorem", because a tennis racket is a good example of a physical object with three widely separated moments of inertia. If you look in [this video][1], you can see the 180 degree flip you describe taking place here on Earth. The interesting difference between Earth and space is that, on Earth, it is difficult to watch an object in free-fall for more than a second, so you only see a fraction of the orbits described in Marcos and Victor's answers; the video I link to looks like about half an orbit. In space, you can see the cycle happen several times.

There are tons of proofs of the tennis racket theorem online, [here][2] is one. 

This question was also asked on [physics.SE][3]; the answer there linked to [this nice paper][4].


  [1]: http://www.youtube.com/watch?v=4dqCQqI-Gis
  [2]: http://isites.harvard.edu/fs/docs/icb.topic455971.files/l21.pdf
  [3]: http://physics.stackexchange.com/questions/17504/why-does-this-object-periodically-turn-itself
  [4]: http://math.ucalgary.ca/files/publications/cushman/tennis.pdf