Orac has a rather thorough post on eugenics, and what Richard Dawkins has recently had to say on it. Here is the dictionary.com definition of eugenics:
...the study of or belief in the possibility of improving the qualities of the human species or a human population, esp. by such means as discouraging reproduction by persons having genetic defects or presumed to have inheritable undesirable traits (negative eugenics) or encouraging reproduction by persons presumed to have inheritable desirable traits (positive eugenics).
First, in a historical context Dawkins' addressing the question of eugenics makes sense. His intellectual forebears, William D. Hamilton and the great R.A. Fisher took a great interest in the topic. I have commented on Hamilton's perceived nuttiness in this area before, reading a lot of his work you often get the feeling what was he thinking, saying that! In my interview with David Haig he was reluctant to even comment on Hamilton's ideas (see question #6). Fisher was a eugenicist who practiced what he preached, raising a large family because of his beliefs. But, a note, Fisher emphasized positive eugenics, Hamilton's most alarming comments (e.g., mooting infanticide of the unfit) tended to be fixed on negative eugenics. Negative eugenics has a long and unfortunate track record, with the Nazi genocide being its apotheosis. In a contemporary sense eugenics will happen. Genomics guarantees that people will selectively abort and sift through their embryos. The abortion of fetuses with Down Syndrome is not eugenics because these individuals cannot reproduce, but that is "proof of principle." So it is important that intellectuals do discuss and address these topics so as a society we make decisions in line with our universal values. A peculiar aspect of modern testing is disassortative mating of individuals with unfit combinations. The testing of Jews for recessive diseases actually is anti-eugenical in that selection against the deleterious allele is prevented. Finally, evolutionary biologists allude to eugenical ideas in personal communication all the time. Not that they do anything about it, but it isn't like it isn't in the scientific Zeitgeist ready to "break out." Just wait.
