Tried using but gave up. It doesn't support all the native API features. So starting to develop an app using Python would eventually end up just re-writing it using Java. So just used Java to begin with.
>Ruboto allows you to run Ruby scripts on Android devices. Using Ruby code, you have access to the complete Android API. Currently, we have 2 offerings: ruboto and ruboto-irb. Ruboto is based on JRuby.
The sl4a Ruby interpreter is based on Ruboto. So accesing the Android API with Ruby is posible. JRuby is Java after all, check their site.
P.S. I wish I had the skill to help out in this project.