After this image whetted my curiosity, I had to try out this photomerge thing for myself. I happened to have a set of photos I took of Roger Williams Memorial Park for research during one of my studio projects, and so I plugged them in to see what came out. Pretty cool!

Click on the image to see a larger version. This is still one third the size of the original, actually, because it creates a layer for each image that its trying to stitch together. I can only see a couple of really obvious places where the image doesn't match up, but otherwise I think it came out really well!
(This image captures pretty much all there is of the park - its one of the smallest national parks in the country! It marks the spot where Roger Williams made his first settlement, as well as the location of the freshwater spring that supported the community.)