I have Amazon Prime, so I can watch now on my computer, but it appears that I don't have anything (at the moment) that will let me stream to my TV. I may have to buy something like the Roku XD Streaming Player 1080p
Amazon: Main Page
[UPDATE: Engadget says the quality of the video is okay, but not great.
UPDATE 2: Just watched a bit of Silverado. Impressed that it started so quickly - I figured they'd be deluged right now - and quality is just okay; Standard Def, not HD
UPDATE 3 10PM: Looks like you do get HD versions. Waiting a minute or two at full screen, the resolution improves on my computer (hard to tell whether 720p or what it is, but it's pretty good, and a friend with a Roku says he's getting HD on his TV set.]