http://us.wii.com/iwata_asks/nsmb/vol2_page1.jsp
Some of the more interesting facts:
-Most of Mario 3's developers did not want Raccoon Mario
-The original Zelda and the original Super Mario were developed at the same time by the same team; Zelda was originally expected to release first.
-The arcade game in Mario 3 was the team's compromise for putting some kind of simultaneous multiplayer in a Mario game.
-World 1-1 in the original Mario was the last level they created.
-The trick for making Mario move smoothly was created by HAL, not Miyamoto's team (Miyamoto to staff: Why do you have to go to another company to find this stuff out?")
-Goombas were the last enemy created, and they only exist because some found the turtles too hard.
-The "P" in "P-wing" stands for "Paratroopa."
-Miyamoto and Nikaga slept together! 
