I got my Netflix disc for the PS3 and decided to test it. The first thing I noticed when opening it is a big label on the envelope that says "do not return this disc". After I inserted the disc in your PS3 I couldn't find the icon to launch Netflix. It does not auto start, and it's not under the games section where PS3 games are when you insert the disc. Instead the Netflix icon is, logically, in the video section. After you launch Netflix it gives you a URL to visit on your PC. After you visit the URL it pairs up your PS3 with your Netflix account via a 6 digit code. From here you're able to watch anything in your queue that's streamable.
I'm left wondering why Netflix requires the disc to be in the system to stream content. It does not install the application to your system. Installing to your system would make more sense, as then I wouldn't have to insert the disc every time I wanted to stream content. The PS3 has a HD for this sort of thing, I'm not sure why Netflix doesn't use it. Perhaps it will be integrated with the system in a future software release?