Oh yeah, about the Mature Mario thing...
We have to remember a few things about what Miyamoto could mean by 'mature'-
1) 'Mature' could have a different meaning in the Japanese culture. For instance, rather than violent-mature, maybe more intellect-mature. The danger is to assume that Nintendo will jump onto the M-rated bandwagon, which isn't necessarily true.
2) Japanese and English are two vastly different languages, meaning that it is incredibly difficult to effectively translate between the two and retain the original meaning. What trickled down to us as 'mature' could have had an entirely different meaning before passing through the translation digestive system. (This could also explain those goofy Japanese game titles...)
In other words, I'm just as confused as you are. I guess we'll find out about this mature thing when SM decides to make a new game...