I ordered the Netflix wii disc and tried it out. It worked well while streaming over our 802.11g WAP encrypted WiFi LAN. Some of the interface graphics are blocky and ugly, but the movie itself was fine. The control UI uses the arrow keys on a Wii wand.
The Flash stream results are at least as good as what I see on my vastly more powerful iMac, and there's no fan noise. Apparently Adobe just hates the Mac.
You need a computer, iPhone, or iPad to validate your account and manage your queue. I assume Netflix would like to remove that requirement eventually.
Activation took less than a minute. You can stream from one Netflix account on up to 6 unique devices (iMac, iPad, iPhone 4 soon, Wii, Roku, etc).
From their site today, here's a list of the streaming Netflix supports. They're clearly well on the way to eliminating DVD mailing (main problem -- too easy to rip and distribute).
We don't have cable at home, we get 3 DVDs a week for the kids to watch. This gives us some new options. I really don't miss cable at all (we do have free broadcast HD via a D/A converter box and some rabbit ear antennae -- works surprisingly well)).