Deal or No Deal - What do you think?

Much has been written about the game show Deal or No Deal. The New York Times published an article today that discusses the different probabilities involved in certain parts of the show. The guys over at the Freaknomics blog have been writing several entries about the game show, but the latest states that "Being a contestant on this show requires no talent whatsoever."

I'm interested in what the advanced mathematics teachers (there are a few who read this blog) out there think about the show. Take a look at the Times' article and answer a few questions for me:

• What is the principle of mathematical expectation? (simple please)
• How do you think the producers decide where to put the million dollars? Do you think it has something to do with where contestants are most likely to look when choosing a case? For instance, do you think there is a higher probability of someone choosing a case in the middle of the group of models?
  
• Is it possible to use some sort of math to figure the game out and win?

Have a nice holiday. Looking forward to your answers...