As with everything GoT related: Spoilers!
George R. R. Martin is in no rush to finish his stories in Westeros.
Game Of Thrones is based on his series A Song Of Fire And Ice, which he began writing in 2001 and was eventually published in 2006.
He had originally envisioned the series as a a trilogy, but it has no become part of a seven-part anthology, of which Martin has published five entries.
The most recent, A Dance With Dragons, was published in 2011, and took Martin five years to write.
The sixth, The Winds Of Winter, is still to be released, with Martin having teased it's release for years now.
However, he has recently released an excerpt - we're unsure if it's an entire chapter, or just part of one - on his official website, which you can read here.
Spoilers though, as the fates of some on the show and the fates of some in the books are not identical.
He posted to his blog regarding the excerpt: "You want to know what the Sand Snakes, Prince Doran, Areo Hotah, Ellaria Sand, Darkstar, and the rest will be up to in Winds of Winter? Quite a lot, actually. The sample will give you a taste. For the rest, you will need to wait. And no, just to spike any bullsh*t rumours, changing the sample chapter does NOT mean I am done. See the icon above? Monkey is still on my back... but he’s growing, he is, and one day..."
Still no real sign of the book on the horizon, though. Maybe he'll do a Beyonce and just "drop" it tomorrow? You can never tell with Martin, he's unpredictable. But then fans of the books already knew that...