Honestly I've only done work in OpenGL where I scale my graphics at draw-time, however, there are definitely a wide range of resolutions and densities that you need to take into account when creating a UI for Android.
I'd recommend reading this as a good start:
http://developer.android.com/guide/prac ... pport.htmlThere's honestly a very large variety of screen sizes, so Android splits them into 4 categories as far as density goes, that link shows a charge of which screen sizes fall under which density (and therefore, which art would be chosen to be used). If your art scales well, you could just stretch or shrink it, depending on how nice you want things to look.