It's not necessarily a new strategy for Nintendo (Mario and Sonic at the Olympics by Sega, Star Fox by Namco, the Mario Kart arcade game by Namco, F-Zero by Sega, Mario Basketball by Square-Enix, Mario DDR by Konami, etc.), but they're REALLY cranking it up a notch right now, and I'm loving it.
And on top of the games mentioned in the OP, they're going to help market Monster Hunter Tri for Capcom and Dragon Quest X for Square-Enix.
To be honest, if Nintendo really drops a Mario/Metroid/Zelda/Pokemon/Wii super-bomb all in one year, 3rd parties won't stand a chance. So Nintendo's just being a good sport and helping everybody out.
(EDIT: forgot about the Zelda games made by Capcom.)