In school, I learned that the first dramaturg was Schiller. He was helping Goethe out on a play. But they had a difficult time figuring out exactly what Schiller should be doing, so he only had the job a few months before Goethe let him go. In German, "dramaturg" is "dramaturg" (the "g" is hard). In French, it's "dramaturge" (the "g" like a "j"). In Polish and Romanian, dramaturg actually means playwright. In English, people seems to spell it without the "e," but pronounce it either the French way or the German way. Which is strange. It's like when I was a kid, the accepted spelling was "theater." But somehow, by the time out of college, all these theaters were spelling it the French way (or aping the Brits, spelling it that way).
Dramaturg means different things to different people. Some theatres say it's the equivalent of a literary manager. Others say a dramaturg is the person who helps the director with his research- both the history of the era in which the play is set, and the production history of the play if it's a revival. To me, being a dramaturg is more like being a copy editor. You have a piece, you want to keep the writer's voice in in and your voice out of it, you want to keep it accessible and clear. You don't want to leave big black paw prints all over it.
Particularly if I'm working on a good play, being a dramaturg is fun. You get to observe somebody else's writing process, you're the second set of eyes, you help them make the play better. Very rewarding, emotionally and intellectually if never financially, but that's okay. Very like teaching, actually.
But if it's my play, dramaturgs make me really nervous. I had a bad experience with one early on, who insisted a comedy of mine really needed marijuana-induced jokes in it, and I couldn't get away from her fast enough. Would have totally undercut who the characters were, and the world they were in. Or as David Chase had Carmela say to AJ when he was smoking dope at his confirmation party, "You're an animal!"
In the best of all possible worlds, to steal from M. Voltaire, I am blessed with a good director who has worked on new plays before and knows what he or she is doing. That is a complicated enough relationship; adding a dramaturg is like having a third person in bed with you. Of course if it's not my play, it's totally different.