Ben Thompson walks back his earlier prediction of an AppleTV SDK. Putting together articles from Dan Frommer and Chris Adamson, he thinks that there IS a sort of SDK, but that it’s for building streaming channels (which Apple seems to be adding at an increasing pace). We’d love to see a full blown SDK, but the current trajectory does make a lot if sense: robust support for AirPlay-ing content over from iOS devices and as many content channels from big name providers as possible.