The eAudio edition is also available from Recorded Books.
I've had numerous requests for information regarding the Audible release of the book. As of right now, I'm unsure what's happening on the Audible front. I'll do some digging around and post an update as soon as I hear anything.
I hope you all enjoy the book - it's been a while coming! Progress on the third book, Dead Man's Steel, is slow but steady. I'm aiming to have it in your hands - all 200k+ words of it - in the first half of 2016.