What Groupshot does is let you combine the best faces from all those different photos to create the one ultimate shot.
Since all the photos are taken in the same setting and are more or less similar, the results that Groupshot spits out are really good and don't require a lot of effort (it's actually very simple to use).
All you do is take a bunch of photos (either from within the app or just using the regular camera app on the iPhone), then you select an area of a face you want to replace, and the app shows you all the different options you have from the other pictures you took.
Finally, all you do is choose which face looks the best and the app magically stitches that face into the original photo, seamlessly.
Once the final photo is ready you can share it on Facebook, send it by email, save it, etc...
The app just came out today and only costs $0.99.
Get it, it's a great tool to have ready in your iPhone for any family event.
The first photo:
Choosing the face I want to replace:
The stitched image (I prefer keeping the goofy faces :)
These are the original photos:
You can't tell that the final result has been doctored:
Here's a short video the explains the concept: