Netflix has updated the UI slighly. This is independent of any firmware update. The UI is downloaded from Netflix when you start the Netflix app. The WDTV just has a core WebKit interface.
The most obvious changes:
Hitting OPTION to show the resolution now lists as 240 SD, 384 SD, 480 SD, 720p HD, 1080p HD instead of the old Low/SD, Medium/SD, etc…
If you try to back out of the main screen, it now asks if you want to exit Netflix. Before, I think you had to hit the HOME button to get out of Netflix.
Some have reported issues with Netflix not starting, or with multiple episode viewings getting stuck. I wonder of this update may fix some of those bugs, too?