For people who haven't read that essay, I should explain that one of the points in it is that there are two distinct ways to get economic inequality in a society: an ancient zero-sum game where a ruling class appropriates wealth generated by a large number of peasants, and a newer form that is not zero-sum, where some people become richer than others by generating wealth faster. For various reasons, people who write about economic inequality tend to conflate the two sources. But whereas the older sort of economic inequality is bad for societies, the second is, if not in itself good, a sign of a good thing: variation in productivity. (The reason variation in productivity is a good thing is that if you have no variation in productivity, it is very unlikely that the reason is because everyone is highly productive.)

For more details, see http://paulgraham.com/gap.html and http://paulgraham.com/gh.html

So your question becomes, do I think that the economic inequality we see today is increasingly of the old form rather than the new form? No, I don't see any evidence of that, not in the US.