HBO Go has been updated to version 2.0, bringing support for Apple's AirPlay feature to the app. HBO Go users can now stream video from any device running iOS 6 to any Apple TV that’s been updated to software version 5.1.1 or later.
HBO Go has been a feature on Apple TV competitors, such as the Roku, for some time now. Though there have been reports that it is coming to the Apple TV, it has yet to materialize. Until that day comes, allowing customers to use AirPlay to watch HBO content is decent stopgap. Use of HBO Go requires an HBO cable subscription.
I've tried it out and it works fine. You can even use some of the interactive features for shows that support them, like Game of Thrones. Go grab the update, and tell us what you think.