No, they haven't. It's just Apple for now. My Android tablet got me this email today:
Dear Comics Enthusiast,*
We've made changes to our Google Play Android Comics app so pleaseupdate to version 3.6. In this new version, we have a new comiXology in-app purchase system and a great new cart feature, one of our most requested features.
In the new app, you may be prompted to update your payment information to continue purchasing books. This is a one-time action after which you can purchase inside the app.
We've added a*$5 comiXology eGift Card**to your account! You don't have to do anything, just shop for your favorite comic books and graphic novels. Hurry! This eGift Card expires on 5/25/14.