Coming from a Java web application background, I'm familiar with the MVC approach to application structure. Its nice and tidy, and generally easy to manage
Are there any similar models for Android? So far all my sample Android applications have been a bunch of classes all bundled into a single package, I can see this getting messy as the application grows
Do you recommend any structuring to separating classes, and organising the class heirarchy?
I think that using packages for organizational purposes is the way to go. I'm going to refer you to Mihai Preda's Android package name blog post, which has alot of useful and interesting material on Java packages and the Android package (the apk file).