Hate on the Nintendo Wii all you want, but it has clearly made Sony and Microsoft nervous (especially since the Wii has made money since day one, while the 360 and PS3 are still losing money on each sale). This week, Sony announced a PS3 motion controller, and Microsoft announced the Project Natal motion controller. For those not already in the know, the Nintendo Wii has had this capability for over 2 years now (though, granted, the Microsoft approach is a new twist).
I agree that the Nintendo Wii has, at some levels, been a relatively 'weak' platform compared to the others. It lacks HD support, has a fairly thin library of games, and has clunky online support. As a result, the Wii has been given the cold-shoulder by the "hard-core gaming community." The two recently announced, upcoming Mario titles (Super Mario Galaxy 2 and The New Super Mario Bros.) probably aren't enough to improve its reputation.
All that aside, it looks like the "big boys" are playing catch-up to Nintendo's "little engine that could." Maybe Nintendo knows the future more than we think they do...