HBO Go allows customers to stream popular shows from the network, like Game of Thrones, straight to an iOS or mobile device. Show that stream on the app are usually available a few months after initial air dates. Previously customers would have to pay $100+ dollars for a cable TV package, but it seems HBO is trying to make the service available to more customers by charging a small, monthly subscription just for HBO Go.
HBO GO is currently available on a plethora of mobile device including Android, iOS, and even Apple TV, so it's no wonder the company is trying to have its shows streamed to millions upon millions of customers. No word on a specific release date, but folks can expect HBO Go subscriptions to be available some time next year.