I have the Nintendo dongle and it works, kind of..
I have to say I bought it when the Wii came out primary to check the various channels and updates, but I never got it to work as it should.
I found out later on that it works flawlessly with the DS, in fact my brother became addicted to Mario Kart once more after owning it for more then a year, however with the Wii I had problems to find the signal, I had to reinstall the drivers several times(there where 4 to choose from) and still every now and then my Wii can't establish a connection, even though PC and Wii are in the same room a few feet apart from each other.
From my experience, I get an unstable unreliable connection with the Wii, but as I said before a rock solid DS experience.
And I visited the Nintendo support site many times and I tried any possible trick, like disabling firewall or antivirus(heck, I don't have one) and manually configure access point.
Anybody else experiencing this kind of problems ?