Since Rails uses MVC architecture. I was wondering that if we can use Rails to develop a mobile app or any web app.

Out of MVC the 'M' and 'C' won't change to develop the mobile app right?  

I mean the models and controllers will remain the same.

Only the view portion should be changed such that, instead of using html.erb files I want Java or Android SDK or whatever, to provide the UI for the mobile user.

Can someone enlighten me on this perspective?

Also I have been hearing about jRuby does it come into play for our mobile app development requirement?