True, but it was reported on many legitimate news sites as well, albeit probably from the same source. I'll continue to wait and hope along with many others for it to appear.
I would be surprised if an Amazon app appeared on the new ATV. iTunes and Amazon Instant Video/Music are direct competitors and Apple created the ATV to push iTunes.
I would not be surprised to see the app appear. The main thing would be that you would not be able to buy new videos through it since Apple would want a cut of Amazon's price. It would probably work like the iphone/ipad app where you buy on a PC or web browser then can watch on Apple TV.