Nutmeg is a traditional ingredient in Italian Besciamella - the traditional layer of "white" in a lasagna that most Americans use ricotta for. I can easily see how nutmeg could migrate to Alfredo dishes.
I like a very traditional Italian variant of "Alfredo" using dried spaghetti instead of fettucini, and lot's of black pepper.
For my "Alfredo" I don't use cream. I melt a good hunk of butter in a pan with a cloves worth of garlic paste - cooking until the water in the butter evaporates but the butter has yet to brown. Then I add a couple cups of reserved pasta water, and bring it to a boil over medium-high heat. To this I add a bunch of good Parmesan and whisk continuously. I add my slightly undercooked pasta to this thin sauce to finish cooking (making sure to toss and stir constantly to keep the sauce from sticking to the bottom of the pan). As the pasta absorbs more liquid and more liquid evaporates, a wonderful silken sauce consistency develops. I finish it with fine sea salt and lot's of freshly ground black pepper (tossing again), then some freshly grated parmesan on top. It's almost a cross between the flavors/aromas/textures of Alfredo and Carbonara.
Do you think nutmeg is a necessity or adds to the Alfredo sauce in a positive way? 
