http://www.youtube.com/watch?v=SA3rECiRQj0
I'm not sure if that was supposed to be satire or if the person was being serious XD. Did bring up a few decent points. Most of them are probably either jokes on the part of Nintendo or just coincidences (it would have made more sense if King Koopa was a corrupt businessman instead of a king
And here's a flash video of Mario as a communist fighting against evil monsters (goombas) for the freedom of the working class, or something like that
http://www.youtube.com/watch?v=Q_xQ-ns5whw
Also, now that I think about it, Luigi is green, and I've heard that green is supposed to represent Western Democracy... could the game be a parable on how the West (represented by Luigi) is helping Communism (represented by Mario) overthrow traditional life and conservatism (represented by King Koopa)?
Lulz, I highly doubt Nintendo would have put that much thought into the hidden storyline of a game... although, let this be a note to gamemakers everywhere: If you game becomes famous, make sure there aren't weird coincidences in it

