Polygyny or polygamy?

Found an interesting article on Slate.com today about the virtues of polygyny. I had assumed it was the same thing as polygamy but apparently I'm mistaken. It discusses the economic case for polygamy, and gives some examples around the world.

Article here

I think the author is right that if you've got it spread it out a little. (my paraphrasing) I have a hard enough time keeping up with one wife let alone three or four. I guess my biggest question is whether this is a "moral" battle or an "cultural" one.