Netflix has finished its goal of making sure every current video game console can access its Watch Instantly streaming content now that it is shipping the activation discs for Nintendo Wii consoles.
The Xbox 360 has been able to stream Netflix for a while now, and eventually the Sony Playstation 3 was able to do it via an activation disc that you have to put in the console each time you want to use the service. While not as convenient as the Xbox 360 method, it still works well.
Now Nintendo Wii consoles will be able to use the same method as Sony has. You can request the free disc at the Netflix site, and they will ship them out as soon as possible.
While the disc itself is free, do remember that you need to have a subscription to Netflix to use the actual service. Without the subscription, the disc is kind of pointless.