Last year I discovered that Dog Ear Publishing had, without my permission, published my book as an e-book on Google Play. I requested that it be removed as although I had hired Dog Ear to publish a printed version of my book several years ago, I was neither contacted by them, given the opportunity to view the file nor set the price for the e-book (which was listed at a considerably higher price than the $2.99 I typically sell my e-books for). I already have my books available on Smashwords and Amazon.
I later wondered if Google Play was worth looking into as an avenue for promoting my books and found a blog post that covers the process for self publishing an e-book with Google Play. The problem appears to be the discounting. Amazon will lower their price to whatever the lowest price you have your book listed for at other locations. If Google Play discounts your book price, then Amazon will follow suit. You can read the full blog post here. For now, I'll stick with Smashwords and Amazon.
Have you had any experience with Google Play? I'd be interested to hear your comments.