Jonah Lehrer highlights some interesting studies about inequality. This is the most interesting result:

It’s not that the primates demanded equality — some capuchins collected many more pebbles than others, and that never created a problem — it’s that they couldn’t stand when the inequality was a result of injustice.

Glenn Loury makes a similar point in this great dialog about Occupy Wall Street, saying that people begrudge Wall Street and not widget-makers like Steve Jobs because they see what Jobs did to earn his wealth.