What does the Vudu HDX version of Avatar have that the Blu-ray version doesn't? That's right, special features. Typically you don't get 'em with a digital download, but Vudu figured the release of Avatar is the perfect time to change that forever. We're not exactly sure what features will be available, but at free, they are priced just right. This is yet another sign that Hollywood is warming up to digital delivery -- the first sign was that digital download customers don't have to wait another 28 days like Redbox and Netflix -- and Vudu also reminds us that if you want to stream Avatar in HD it is them or the Playstation as all the other streaming services will only offer the movie in SD -- we don't know about the Playstation service, but Vudu's HDX certainly qualifies as real HD. Another pictures of the Vudu interface after the jump.