As a 'purple' owner of both formats, I've been giving the HD-DVD camp as much slack as possible in the "rumors of my death are premature" tug-of-war that's been going on since the Warner announcement...
But this is a huge sign that the end really is near.
As suggested above, Netflix doesn't make a decision like this in a vacuum. They've had to have been privy to some info on Universal and Paramount's plans to make a decision like this as they've ALWAYS prided themselves on being a rental customer/completists dream...i.e. if it's out there, they carry it. This shows they see the writing squarely on the wall for the format.
I empathize w/ the red-only crowd. The films A/V quality are often stellar, but just remember that you'll get to enjoy them for a while to come--the benefit of digital disc. Not like its a tape format that will wear-and-tear and suffer dropouts, etc. So chin up, buckaroos. And by the time you've licked your wounds sufficiently, the Blu-ray players will be even cheaper and there will be more titles to choose from.