Well, one major way in which both the PS3 and 360 are much more like traditional consoles than they are like pcs and in which the Wii kind of stands on its own grounds which might be quite different than any previous console is "Comfort" of use.
Traditionally when playing consoles, you are able to sit and relax in an easy chair with your feet propped up if you want to prop them up. This is radically different from desktop pcs where you have to sit at a desk in a stiff chair not very far from the computer screen and laptop pcs that (in my estimation are not generally built for gaming). Also, the Wii's most popular games fly in the very face of this concept as you have to stand up and move to play both Wii Fit and Wii Sports (and most likely the upcoming Wii Sports Resort and Rock N' Roll Climber ( I think that's what it is called).
Due to six-axis motion control in certain games, you sometimes have to stand up to more effectively make the proper motions in some PS3 games too -- more than 360 but much less than Wii.
So, I would say comfort of use is one major way in which both PS3 and 360 are much more like traditional consoles than they are pcs and in which the Wii is moving in its own direction where having to be more active, which was never a major component of most prior consoles, to have to control many of its games is a new aspect of its design that I'm not particularly fond of, and I am worried that the popularity of the Wii may push the other consoles in this direction.
IMO, playing games is supposed to be about how good you can make the onscreen avatars behave through your skill at controlling the game with a joystick or gamepad while being able to be as sedentary as possible. Not about controlling a platformer, for example, while running in place and jumping on a balance board using your own athletic prowess to control the game.
Video games are to be controlled cerebrally not physically.
