HBO has a ton of shows on iTunes, so it's not out of the question.
I have Comcast at home for TV & internet - and their Xfinity TV app lets you watch Game of Thrones from inside it as long as you subscribe to HBO at home.
Might not be the best solution, but the app is available for Mac, iPhone & iPad.
HBO Go is available early next month and will allow similar viewing.
First episode seems to be free if you're not already a customer.