On a rough analysis basis, the connection ratio of Wii is around 35%, in the Japanese market. And that of DS is probably, 20% or so. It had increased with the measures like Nintendo Zone with McDonald's to lower the hurdle for connection, but has not reached the 30% mark. ...Most radical people even dare to say that retailers will be replaced by digital distribution in no time. But personally, I think it will still require a significant amount of time. In other words, it will require many years and months for the majority of video game purchase to become digital. In short, in 20 years or so I might say it will have probably changed. But in 5 years or so, I do not totally agree with opinions that no one will purchase titles at retailers by then. Habits of life do not change such radically and quickly. Especially for the expanded audience of various people, to whom we are and will be trying to appeal, I believe their habits will change more slowly. - Satoru Iwata

I'd have to say that that's a pretty low connection rate for the amount of install base. I'm willing to bet that the 360 sees a much, much higher number. I just don't think Nintendo's online setup is very compelling right now. Even with the elements that are interesting, they are so hidden from the average consumer that they don't even know to go online and hunt them down.

Link