I am reading a lot about apps, and I dont see the advantage if apps cant talk to each other. In the normal sp 2010 farm solutions you create content types, lists definitions etc, and then you can create list instances that uses those definitions in any web or subweb.
Sometimes I have seen requirements when an item is added in one list, something else needs to be calculated in another list.
With Apps, is that possible?(if the lists are in separate apps) I guess the app should have Site Collection permission which is way too much permission, no?