I've tried adding pineapple skin to my coals before, but if I remember right, I couldn't taste that much of a difference. The smoke smelled a little sweeter, but I don't remember any flavor imparting into the meat. I guess if you used pineapple planks like DM used though, you would be able to get more flavor.
Oops... I see where the article was about the planks now. My bad. I have seen people use the skin itself in coals before too, but I personally haven't had significant results with that.