Microsoft Research has released Face Swap over at the Windows Phone Marketplace that allows you to swap people's faces around in photographs. Face Swap uses multiple face detection to identify everyone's faces and with a shake of your Windows Phone, the app swaps the faces around.
Once you've created your newly arranged photo, you can save it to your Photos Hub or share it directly to Facebook or Twitter. Face Swap is a free app that you can grab here at the Windows Phone Marketplace. It is a mango app so you'll need to be running Windows Phone 7.5. Face Swap is sure to make for interesting Holiday group pictures.