You might call this scientific brain drain, but I rather consider it the competition of the brightest brains for the best possible places in the world to do research. I do every year a two-weeks summer school on "Molecular Mechanisms of Radiation Carcinogenesis", which over the last ten years or so attracted more and more students from all over the world. This years class had participants from China, India, Iran, Turkey, Romania, Serbia, Sweden, Germany, Nigeria, Ghana and the US (please note I listed the countries in the order of the rising sun, i.e. from the farest east to the farest west).
I have to say that they were all extremely commited to the lectures they heared here, and since they returned to they home institutions or continue their PhD projects anywhere else, it is not a brain drain from the poorer to the richer hemisphere of the world, but rather the spreading of scientific knowledge.
I strongly believe that anything that mankind has discovered or created should be available for no costs to everyone, because only this way this and all future generations can profit from scientific discoveries. But I not only want to advocate a world-wide benefit from the discoveries of a few brilliant researchers (such as Harald zur Hausen or Emmanuelle Charpentier), but I strongly believe that an unlimitted access to the creative pool of the whole world will speed up and nourish any further progress, be it scientifically, technical or cultural.