The app includes a step-by-step guide explaining how everything works.
We tried the app with AAWP's resident cat (who responds to the name Mac, or the opening of a cat food cupboard, the latter with more alacrity), but sadly we were unable to elicit much enthusiasm (sitting on the phone doesn't count). Do let us know in the comments if you have better luck. Alternatively check out this Lumia 1020 captured cat photo.
Fortunately, the developer, Igor Kulman, has provided some sample screenshots, so you can see what the app looks like in action:
Looks like it's the cat's whiskers. It's almost as good as having an official Snapchat app...
Windows Phone Store description:
Snapcat: an app that lets your cat take self photos. Your cat will chase a laser on the screen with its paw, taking pictures at the same time.
Snapcat is a free download from the Windows Phone Store. Due to the cat detection API requirement Snapcat is only available for Windows Phone 8.