Playstation 3 is very close, but it's not open enough. It's not nearly as easy as using a computer to navigate content or add apps. The UI for the PS3 is definitely closest though. Windows, Mac, or Basic Ubuntu just don't work for the living room.
Wow, that's really interesting that Netflix is that important for distribution. Well, moreso that it's that much ahead of the others. I really wish they would have the PlayReady DRM work on linux, not because of desktop linux being so popular, but the plethora of devices that could be built on Linux using Netflix.