Well, I wouldn't say Sony is in on the dominating.
Last 3 months:
Wii: 1.9M
Ps3: 1.0M
X360: 0.8M
In Americas, this is the situation.
Wii: 1.9M
Ps3: 0.8M
X360: 1.0M
So then, you would have to say that in Amercias, Nintendo and Microsoft are dominating, with Sony lagging behind.
As for what Microsoft can do, I think they're content with their sales - I mean, it is the area where the X360 has improved the most over what the original XB did.
http://www.vgchartz.com/games/userreviewdisp.php?id=261
That is VGChartz LONGEST review. And it's NOT Cute Kitten DS