Easter Eggs, they're nothing new. But random messages from the President of Nintendo tucked away in a game of Metroid? Very new. And kooky. Above is a short clip from Metroid Prime 3, featuring Satoru Iwata's cameo appearance in the game. Don't speak Japanese? He's saying:
Hello, this is Iwata from Nintendo. You may not know from an outsiders point of view, but being a director is really hard! When things are really busy and stressful we (us directors) may look tired and sick, then people may feel sorry for us! But in my case, it's the opposite, I get fatter and fatter, so then people don't think I'm stressed at all!
Nothing to do with Metroid, at all, which only makes it greater.
Metroid Prime 3: Corruption - hidden message translated [Go Nintendo]