I have two users on my Mac, myself and my wife. One of the things that really bothered me with iPhoto is sharing photos between users. Depending who dumped the camera, that person would get that roll. Some photos are under my user, some photos are under her user.
With every new iPhoto release I would hope Apple would address this issue. Well, it turned out they addressed it a long time ago. iPhoto has the option of sharing your library using Bonjour discovery. I always associated this feature with sharing photo albums between two machines. But with fast user switching, you can have one iPhoto sharing its albums between users.
Just turn on photo share under one user and the other user will see every shared photo. It’s fantastic.