While technically true, in reality, it's actually a bit of a myth, I believe, as the forces are too weak.
(I saw it on snopes.)
Rotation has a lot more to do with drain design than anything.
That said, their tropical storms DO spin in the opposite direction. (I think!)
One of my professors was executive officer on the New Jersey (during WWII.) He said that he did this test (on various ships and in various ports) all over the world. Genrally (if the water had some time to relax), rotation went as predicted.
that's atmospheric coriolis effect, which could be explained by the sun orbiting the earth.
a large enough drain in a controlled environment would certainly prove the earth is itself revolving