The iPhoto Library Manager is a utility to create and manage multiple libraries in iPhoto. One of painful things about iphoto is that you only have one library and that is set by default. There are hacks for moving a iphoto library, you can simply move it using the finder from one location to another and when its booted up iphoto's confusion will prompt you tell it where the library is now. This solution is slightly less hacky and allows multiple users to access a single library, plus you can now have network mounted libraries with *nix permissions and so on. It really opens up the potential for using iPhoto in a workgroup or just managing multiple computers each with iPhoto.