The DS has heavily introduced on the home console market in Japan.
As for attachment rates, it's only been out for a year. Attachment rates increase throughout the life of the console. The current 3:1 will be 4 or 5:1 next year and so on.
It should also be noted that 3rd party developers were caught with their pants down by the Wii. Game development begins a year or two before the game is released and most developers/publishers put most of their efforts into the upcoming PS3. Because the PS3 eats up so much development resources, not much was left for Wii and because they didn't anticipate it to sell so well, they had allocated even less resources for it.
Now that it's a hit, developers/publishers have reallocated their resources appropriately (read: Capcom moving Monster Hunter 3 to Wii for example). Because development time takes a year or two, we won't see this shift until later this year.
The rEVOLution is not being televised
