My DD did this last summer and absolutely loved it. You get to eat with one of several Imagineers working at WDW. The Imagineers rotate so they each do a couple of lunches or dinners a month. You eat in a special room in the Brown Derby and the meal consists of an individual Cobb salad, a choice of one of three entrees, dessert, and non-alcoholic beverage. I believe my DD ordered the filet and she mentioned that one of the other entrees was the Thai noodle bowl. You will also receive a souvenir plate that celebrates 50 Years of Imagineering. It is a LARGE black plate with gold lettering and the Imagineer will sign it for you. The charge last summer was $60 plus tax and tip. A dinner is also offered and that includes wine pairings with each course. The last price I remember for this was $100 plus tax and tip.
I believe my DD ate with Jason Searle(I think that this is his name). He is considered a "show writer" and has written many shows at WDW including "Who Wants to be a Millionaire". He also wrote a collector's book on The Haunted Mansion movie and told my DD that he was currently working on a book about the Pirates of the Caribbean movie.
This is one of the best gifts that I have ever given to my DD and the money spent was well worth it. She plans on doing the dinner on our next vacation this summer.