Okay, I admit I was wrong. Comparing them all side by side, I'll finally admit there's a difference. I don't think the difference between 30 FPS and 60 FPS matters much, but whatever.

http://boallen.com/fps-compare.html.

http://i.minus.com/iuHMClLCinzEh.gif.

Just because your eyes doesn't notice the difference, doesn't mean that your brain won't. I've never cared too much whether I'm playing in 30 or 60 fps myself, but truly there is a difference.