Eugene Volokh has an interesting post up called Selecting for Intelligence as Causing Societal Inequality, where he makes some arguments against the idea that genetically engineering children (ala Gattaca, which is one of my favorite Sci-Fi movies) would cause social inequity.  Among other things, he states:

It might even be an argument against smart people deliberately seeking out other smart people to marry, which is basically a lay form of genetic engineering. Would you therefore urge "breeding for equality," in which smart people self-consciously try to marry dumb people, so their kids wouldn't have too much of an unfair advantage? Or how about programs that try to persuade smart men that the feminine ideal should indeed be the dumb airhead woman (and, of course, to persuade smart women that they should marry dumb men)? True, there might be a significant difference in degree between the IQ benefits to be gained by genetic engineering and the IQ benefits to be gained by lay genetics or education. But I stress the "might be," and in any event the principle strikes me as quite similar.

He's got a point (and be sure to read the whole thing).  So then, all people who believe fervently in social justice should seek out those on the other side of the intellectual and economic divide to marry.  That way, with every generation, we'll grow closer and closer to uniformity.  Rich people should find a homeless person in an alley to marry, which has the added advantage of raising the class of the poor homeless person immediately.  Members of the different races should all marry outside their race, so that one day there would be no races at all... or culture I'd imagine.

Just imagine what our world would be like if all the color and variety were replaced with gray.  I'm imagining a damn boring place myself.