I've seen this discussion come up on HN a few times so I think people may find Tyler Cowen's talk on this subject interesting.

Some interesting bits of information:

- People do work less to some extent, but the reduction in working hours is concentrated in teen years and old age (65+).

- People seem to like work, will continue their jobs even if they win the lottery.

- Rich people (top 1%) now work longer hours than poorer people.