Via Tyler Cowen, a paper attempts to see who's earning the big bucks:

We consider how much of the top end of the income distribution can be attributed to four sectors – top executives of non-financial firms (Main Street); financial service sector employees from investment banks, hedge funds, private equity funds, and mutual funds (Wall Street); corporate lawyers; and professional athletes and celebrities.

Their analysis suggests that "Main Street" CEOs -- the heads of firms outside the financial sector -- comprise a relatively small proportion of the super-rich (obviously, CEOs earn a good deal of money) citing such factoids as "the top 25 hedge fund managers combined appear to have earned more than all 500 S&P 500 CEOs combined (both realized and estimated)."