The best treatment of this topic that I found was in "The Winner-Take-All Society: Why the Few at the Top Get So Much More Than the Rest of Us" by Robert H. Frank and Philip J. Cook: http://www.amazon.com/dp/0140259953.
There is a lot to say about this topic, and I feel that the authors do a great job. A few things that I remember about the topic right now:
While the most actors might make millions of dollars a year, this does not represent the compensation of most actors. For example, salary.com lists the median income of "actor/performer" at around $50,000 a year, and the 90th percentile compensation at $72,000 a year. A nice living, but hardly millions of dollars!
Another way to look at this data is that, in these fields, a very small increase in ability leads to a dramatic change in compensation. For example, winning a race in the olympics might lead to several lucrative endorsement contracts for the athlete. But finishing second, third or fourth might lead to no endorsements at all. However, these races are often so close that we need a computer to tell us who won!