Do Android developers have to create multiple versions of their apps as well or does Android automatically scale them up or down depending on resolution?
There is no need for multiple app versions, although some developers offer them to charge extra for the HD versions. Basically you have to support low, medium, high and extra high density screens. Android will do its best to scale the app but the result isn’t always great. Also good apps should adapt to the form factor, for example a single view for a phone and a two column layout for a tablet. It’s not easy to get everything right. That’s why there are many app which are only optimized for phones. Those look bad on tablets, especially the Nexus 10. A really well designed app will look great on an Android phone, 7" and 10" tablet. But ain’t nobody got time for that. :P This is a quick overview what a developer has to take care of when supporting multiple screens: http://developer.android.com/guide/practices/screens_support.html