So I've kludged together something together on Android that can be kinda sorta called a Warmshowers app!
At this stage it requires quite a lot of messing about with it. However, a significant advantage (imho) over the iphone app is that it doesn't require a data connection to see what WS hosts are nearby.
I am hoping to get some people to help me test it out. I modified an existing open source app (and I know squat about java, tbh), and as such I have little control right now over usability aspects of it. however, I can forward on any comments to the maintainers of the project it is based on.
contact me directly for an apk and associated files and I will be happy to send them to you.