Yeah, there are all kinds of interesting things that can be done with shared data like this. But the first step is to have some standard ContentProvider to let apps share the data locally on a single device, similar to how other user data is handled. Because I'm tired of having several map apps installed for various reasons that all have separate favorites.
Once that is in place, people can create apps that build on it in lots of different ways.
Once that is in place, people can create apps that build on it in lots of different ways.