Than just showing a larger image in a blog post. At least that is where I am seeing it in my install. Is it used anywhere else? With a little bit of coding; I can have a very nice slideshow view of the photos in photo albums. I am thinking of dusting off my fancybox plugin for TinyMCE; even with the bug it has, to allow my members to shrink photos in a blog post and have a fancybox pop-up of the larger image. You can even open videos in fancybox as well as iframe and ajax content.
For those interested in what you can do; http://fancybox.net/