This is mostly true with Xamarin also, platform code is platform code. Most of your code sharing is business logic/accessing rest api's/core algorithms. UI/platform type of code is always going to be hard to port. That being said MacRuby (which is basically what Ruby motion is and JRuby (ruby on the jvm which I think the Android is based upon) are pretty close to source code compatible last I checked so I think it's likely a good chance.

And what are the chances they get all the Android Ruby stuff to work perfectly in the initial release? As opposed to 6 months later after the bug fixes are deployed; hope you didn't have a release window for that fall 2014 app!

(Perhaps I'm overly cynical, though I've seen this before on other platforms.)

Actually I'd say pretty good as their software has been really high quality so far. That and the fact that JRuby already exists and I'm pretty sure thats the target runtime, a lot of their work is already pretty solid.