This feature would be very welcome for us as well, in this case we would like a wider approach of the functionality.
- Users of Group A can view a specific calender in Outlook, we would like to be able to create a custom livetile app with permissions so that the users don't have the configure the livetile by themselves.
- Users of Group B can view a specific document library, we would like to be able to create a custom livetile app with permissions as well.
This way you can publish livetiles with content that only applies to a specific range of users.
I know this can be arranged when you apply these livetiles in separate groups, but in some cases it comes in handy that you can apply permissions to livetiles because both users are member of the same group.