Actually, there are a lot of people who misunderstand it as Napoleonic ice cream or just Napoleon ice cream. (actually, my friend's mom thought that Napoleon Dynamite was called Neapolitan Dynamite, so I drew her a picture of some strawberry, chocolate, and vanilla flavored dynamite. But I digress.)
The type of ice cream which became Neapolitan ice cream was at first called spumoni (made of cherry, chocolate, and pistachio ice cream), and was only popular in Italy in the 1870s (clearly far beyond the period in which Napoleon was in power). The ice cream, imported to America in the 1890s, was in fact from Naples, the city in which all spumoni ice cream was made. As the ice cream progressed west and its flavors changed, it became known as Neapolitan ice cream to commemorate the city of its origin.
