It'd rarely be the right thing to do, anyway. iPhone apps strongly tend toward drilling down through a hierarchy of list views until hitting a full-screen (incl

It'd rarely be the right thing to do, anyway. iPhone apps strongly tend toward drilling down through a hierarchy of list views until hitting a full-screen (including controls along an edge) detail view. iPad apps on the other hand have a flatter hierarchy, very often showing a list view and a detail view (for the selected item from the list view) at the same time. This is why iPad apps are more likely to implement a "real materials" style of interface... they're less explicitly about drilling through hierarchies for data and more about direct manipulation of the entities the app deals with.