Yeah there's an app for this. AutoStich... does what it says, stitching photos you take on your phone into a single panoramic image. When taking images you need to remember to move the phone... not your body. Also make sure there are enough features / overlap between images.
I tried this out for the first time at the pig roast and got some good results. Some of the blur between images makes for some cool stuff. Also I've cropped most to remove the black border introduced as it stitched the pics together. Most of these were made with about 8 - 10 shots and took a minute or two for the phone to put together.
Be sure to look at all of these in their full size glory within my OPR panorama set... lots of little details to pick up!!