I did some digging and found
Fair Labor Standards Act (FLSA) Coverage (Exempt vs. Non-Exempt -- The Online Wages, Hours and Overtime Pay Resource which gives all the details of flsa in it's legal glory.
According to that, an exempt employee pretty much has no protection whatsoever. No guaranteed lunch breaks, no protection from being required to make up lost time, no guarantee of extra pay...
That said, I make straight time for time over 40, usually in the form of Comp time. I will work a maximum of 24 extra hours per month and that is if my schedule permits.
Unless my finances change drastically or the economy tanks so that I can't find another job, the day I don't get credit for it in the form of time, money, or an equal incentive (a company car, perhaps) will be the day that I am no longer able to work anything over the 40 in my contract.