FWIW I think this is a really interesting announcement. Unlike live and the PS3 network, I think Nintendos setup really does open up possibilities for new business models.
It's practical for a small shop to build live or PS3 online games, but they are still a considerable investment and require a publisher to get your product out the door. If what I'm hearing about the Nintendo setup is accurate then it would be a much smaller investment and no publisher required. It looks like Nintendo has some rules in place that should stop the big boys saturating the market overnight, and at least allow the small guys to have a shot.
The big question for me is with no QC at the Nintendo end will the dross drown out the stuff that's worth playing and make it difficult to find the worthwhile titles. Effectively making the service worthless. I'd heard that part of the reason that MS started requiring a publisher for live games was as a first level filter to reduce the number of crap concept submissions they were seeing.