I have came up with this post but it is for the deprecated Google Maps API
http://tech.truliablog.com/2012/02/23/custom-map-markers-for-android-google-maps/
Chris Broadfoot created a utility library that does exactly that.
The library is available here: https://github.com/googlemaps/android-maps-utils
Also see this short video: http://www.youtube.com/watch?v=nb2X9IjjZpM