A friend described a situation where this software might prove useful.

Apple's iPhoto is a convenient application to use to organize and edit your digital photos, but it restricts you to having to keep all of your photos in a single, monolithic library. When your photo collection begins to grow, having all of your photos in one library can become unwieldy. iPhoto Library Manager alleviates this problem by allowing you to keep multiple iPhoto libraries in different places on your computer (or even on an external drive or networked volume) and switch back and forth between them. It also provides at-a-glance information on each of your libraries, allows you to copy photos directly from one library to another, merges entire libraries together into one, and syncs photos from multiple libraries with your photo capable iPod.