There's now cover art. It went through a few iterations. I rejected Amazon's first suggestion for reasons I don't want to get into (if you can't say anything nice...) and the second one they had trouble getting the model rights to. For the third one, they let me pick the image (I'm still stunned I have any input in this. Woot!) and this is the one I liked the most out of the options they gave me.
The cover is by Anne Cain, just as with the first three books. I really like that they have continuity between the books of the series. Here is the full front and back image, with the description on the back:
I really hope everyone likes this book when it comes out, and if you do, tell all your friends. Whether book five or any later books come out is directly dependant on this one selling enough for Amazon to want to buy them. Not to pressure anyone, but it is a fact of life.